FISHERIES RESEARCH BOARD'OF CANADA

Translation «Series No. 1026

!)

'/

ContributioeU the knowledge of the suprarenal capsules in the Cyclostomi. / On the suprarenal capsules

of the Petromyzonti

By E. Giacomini

Original title: Contributi alla conoscenza delle capsule surrenali nei Ciclostomi. Sulle capsule surrenali dei Petromizonti.

From: Monit. Zool. Ital„ Vol. 13, pp. 143-163, 1902.

A

Translated by the Tfranslation Bureau(MB) Foreign Lanages Division

Department of the Secretary of State of Canada

Fisheries Research Board of Canada Halifax Laboratory, Halifax, N. S.

1968

37 pages_typescript

;.1

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0427 Italian

4 March 18 / 1968

E. GIACOMINI

CONTRIBUTION TO THE KNOWLEDGE OF SUPRARENAL CAPSUIRS IN THE CYCLOSTOMI

ON THE SUPRARENAL CAPSULES OF THE PETROMYZONTI

(with Tables

SOS-200.-10...31

1011.7 iS•

E. GIACOMINI

CONTRIBUTION TO THE KNOWLEDGE OF SUPRARENAL CAPSULES IN THE CYCLOSTOMI

ON THE SUPRARENAL CAPSULES OF THE PETROMYZONTI (with tables II-II1)

Received May 3, 1902 Reproduction forbidden

Research on the suprarenal capsules of the Cyclostomi

date back to 1827, when Rathke (30), though remaining comp1ete-/143

ly uncertain of their significance, called attention to two

glandular organs in the Petromyzonti, situated opposite the

heart, at the beginning of the abdominal cavity, and pressed

against the venae cavae.

However, from that time up until the prescrit, in spite

of the gradual improvement in tools of research, the presence

of suprarenal capsules in the Cyclostomi has never been satis-

factorily demonstrated, as may readily be assumed from the

brief bibliographical notes which follow and which deal with

our subject.

J. Mueller (1845) (26) believed he had found them for

the Ilmln2 in two special glands, to the sides of the heart, and considered as kidneys by Retzius. He thought he saw homo-

logous organs in Ammocoetes under the form of those white bungs

already mentioned by Rathke, pressed against the trunks of the

cardinal veins, while he was unable to find similar organs in

EeImmun. Subsequently, J. Mueller altered hi s opinion, main-

taining that those glands represenbed the thymus gland.

/2

..... .... .... . .

'''''

/2

Ecker (1846) (8), after recalling that Retzius consi-

ders the two glands to the sides of the heart of the Myxine as

kidneys, establishes, agreeing in this with J. Mueller, the

homology between those glands and the white bungs described by

Rathke in Ammocoetes. However, the existence of suprarenal 143/ 144

capsules has not been clearly demonstrated even by Ecker. In

Petrom, zon marinus, he found a yellowish organ with blotches

of pigment to one side, between the large veins of the body

and the aorta. The two organs begin behind the cartilaginous

pericardium and extend to the rear extremity of the abdominal

cavity. Ecker was at first inclined to consider these organs

as suprarenal capsules, but later, realizing that their micro-

scopic constitution xxx opposed this opinion, he was forced to

leave their nature completely in doubt.

W. • ueller (27), who in 1875 studied the pronephros in

young Mmine, in Ammocoetes, Petromyzon fluviatilis and P. Pla-

neri, makes absolutely no mention of suprarenal capsules.

Weldon (1884-85) (40), basing his remarks on a few struc-

tural details of the cephalic kidney of Bdellostoma, formulates

the hypothesis that a part of it may have been modified in such

a way as to form an organ functionally similar to the suprarenal

capsulesG

Pettit (1896) (28) again finds the organs indicated by

Ecker in Petromyzon marinus and concludes that "in the Cyclos-

tomi, behind the gills, on each side of the heart, there are

special glands which are closely connected with the aorta and

the vena cava, but it is not possible to determine whether

/3

or not these are organs comparable to the suprarenal capsules

of Mammals" (1).

Collinge and Vincent (1896) ()+) in a pertinent work "On

the so-called suprarenal bodies in Cyclostomata", examined speci-

mens of nxine_alutiposa, Petromyzon marinas, P. Planer! and Ammo-

coetes. In Petromvzon marinus, they saw the triangular bodies

described by Ecker, but were unable to find any trace of glandu-

lar structure, even upon examination under a microscope, and con-

sidered those bodies as embryonal connective tissue, perhaps osto-

gen. They confirmed the presence of the white bungs, of the

bodies described by Rathke, which, from the microscope examina-

tion, seemed to be formed of connective tissue. "It is possible,"

write the two authors, "that those bodies were once glandular,

but degenerated. We are unable to say whether they have anything

to do with suprarenal capsules".

In specimens of Ammocoetes, they found Rathke's white

bodies, which, though consisting of connective tissue, were, how-

ever, considerably larger than those found in adults of Lumnum marinus. A pronephros would seem to be lacking in Petromuon and

the supramrenal capsules have perhaps degenerated in the Cyclos-

tomi.

The totally' negative conclusions arrived at by Collinge

and Vincent, after dealing with the subject in such a special man-

ner, would lead us to suppose that every new attempt at research

on the supranenal capsules in the Cyclostomi is useless, although

4 (1) From Pettit's description, we :ire unable to determine

to which glands he is referring.

7- : -!!!!%'•

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/4

nothing could convince us of the absence, in these Vertebrates,

of organs of which the high morphological and functional value

in the Gnathostoma is becoming ever more evident with the find-

ings of new observations.

Suspecting that means adequate for the purpose had not /145

been employed in research on suprarenal capsules in the Cyclos-

tomi, and that material in a good state of conservation had not

always been used, and that these were the reasons for the un-

successful results of all previous investigation, I wanted to

resume the study of the subject, carrying out a methodical exa-

mination in Petromzzon marinus, P; Planeri and Ammocoetes, in

varying stages of development. It is true that the work has been

long and tedious, but in compensation, it served to bring to

light organs of such particular structure, arranged in such a

particular fashion, that, if 1 am not mistaken in my interpreta-

tion of their morphological significance, may represent a very

primitive stage of the suprarenal capsules in the Petromyzonti

and may also explain the presence of cellular nests, of chromaf-

fin cells, that is to say, of that tissue which is similar to

the medullar substance of the suprarenal capsules, in the ganglia

of the sympathicus even of higher Gnathostoma and in regions of

the body which have apparently lost all connection with the

suprarenal capsules.

Reserving all more detailed description to the work

which, accompanied by more elaborate illustrations, is to be

puublished in the Italian Archives of Anatomy and Emryology, I

shall limit myself to summarizing the principal results of my

/5

observations.

I shall first of all deal with arrangements in adult

specimens of

Petromyzon marinus

Both essential parts of the suprarenal capsules are

present, the so-called cortical substance and the so-called

medullar substance, and extend not only over the entire trunk

region but also to the caudal and cephalic regions. 145/146

For greater clarity, and in order to avoid repetitions,

I shall first mention briefly the arrangements noted in the

medial region of the trunk and then very briefly those found

in other regions.

Medial or renal region. For the purpose of obtaining

initial, precise knowledge of the arrangement of suprarenal

capsules in Petromyzon mminus, it is well to avail oneself

of a series of cross-vertical sections, sagittal and frontal,

made in that part of the trunk corresponding to the kidneys,

and which I shall call renal or medial region.

From the total of observations made on series of sec-

tions obtained in this manner following various directions,

I have found the following.

The cortical substance is constituted by numerous small

solid epithelial lobules, of various shapes (spherical, ovular,

ellipsoidal, or, less frequently however, cylindrical and form-

ing brief condons) situated around the venae cavae (posterior

cardinal veins), but most frequently, and consequently in greater

number, on the ventral and medial wall of the veins, in the

..71"

/6

adipose tissue between the veins and the aorta (Fig. 1, s.c.).

The greater part of these lobules protrude into the lumen of

the veins, from which they remain separated by the vasal endo-

thelium alone. They are all surrounded by their own membrane

and all contain epithelial cells, cylindrical or of varying

polyhedral shapes, or else tapered, in the cytoplasm of which,

following treatment with osmic acid or with fixative liquids

containing it, it is possible to bring to light numerous small

drops of a fatty substance, which, in my opinion, must not be

confused with common adipose tissue (Fig. 3 and 6, s.c.).

Similar solid lobules may be found, though rarely, Eaq

along the course of the renal arteries or in the trabeculae

surrounding the blood sinuses situated dorsally with respect

to the kidneys.

All the aforesaid epithelial bodies appeared to me to

be quite similar to cordons or lobules of the cortical substance

of the suprarenal capsules of the Amphibia, and also to those

of the interrenal body of the Selachii.

The medullar substance (Fig. 1, c.m.) consists of a

tissue which is epithelial in appearance, with the properties

of chromaffin tissue, which, situated to the sides of the

aorta, extends along the parietal arteries which branch off

from it, and also along their ramifications, dorsal and ven-

tral. On all sides of the aorta, between its wall and the

lumen of the corresponding cardinal vein, there is a layer of

tissue whose elements, which are epithelial in appearance, be-

come highly coloured with hematoxylin and hemalumen and also

give the known typical reaction with bichromate of potassium.

'''''' ''''' •

/7

This layer of tissue thickens near the place of origin of each

parietal artery and becomes thinner in the space separating one

artery from the other; it faces the lumen of the vein sinus and

remains separated from it solely by means of the endothelial

covering. It follows laterally the course of the trunk of or!-

gin of all the parietal arteries, always extending into the

146/ lumen of the cardinal vein located ventrally, and when the 147 artery bifurcates, giving origin to its dorsal and ventral rami-

fications, it is distributed along these ramifications, however,

in such a way that ib continues to face the lumen of the parietal

veins, dorsal and ventral, accompanying the respective arteries,

and ordinarily, in such a way that it is still separated from

the vein sinus solely by means of the endothelium. It thus pene-

trates the wall of the body, inside which it rises dorsally to a

point above the spinal ganglia, even surpassing the level attained

by the upper wall of the spinal canal and that of the lateral

nerve, extends itself ventrally into the wall of the abdomen,

following the course of the ventral parietal artery, in the vici-

nity of which it is easily visible, mainly to the side of the

vein lumen, satellite of the artery, towards whose lumen it pro-

trudes, covered by the vasal endothelium (Fig. 4). Given the

connections of which we have just spoken, it is easy to understand

why, in observing cuts affecting spinal ganglia, it is sometimes

possible to see nests of cells near the large ganglionic elements.

I have never discovered the sympathetic nervous system,

either in Petromuon or in Ammocoetes, with the constitution

/8

described by Julin, and I must say immediately that my re-

search did not in any way confirm the existence of true sgm-

pathetic ganglia along the sides of the aorta, as Julin (14

and 15) imagined for the Ammocoetes.

With regard to the connections between the sympathicus

and the medullar substance, I must say that only rarely have

I seen a few nerve cells in the chromaffin tissue which runs

along the aorta, while I have quite frequently observed them

in that which follows the ramifications of the parietal arte-

ries (Fig. 4, c.g.s.).

The layer of medullar substance, in its thin portion,

consists of a simple series of cells which are epithelial in

appearance and for the most part cylindrico-prismatic or cubi-

cal in shape, with demarcations which are not always clear,

especially if fixation was not carried out in Flemming or Her-

mann liquid. In the thicker portion, on the other hand, it

takes on the appearance of cellular masses sub-divided into

small lobules, of which the elements, though epithelial in

shape, may be m2 quite varied in form, sometimes with short

prolungations of their bodies (Fig. 6, c.m.). In this case,

we immediately see the ressemblance which the elements of the

medullar substance of the suprarenal capsules of Petropmzon

bear

renal capsules and the nests of cells in the sympathetic gan-

glia of the Amphibia, and also their ressemblance with those

other elements of which is composed the parenchyma of the

suprarenal bodies of the Selachii.

with those making up the medullar substance of the supra-

• =7-7 ,777,12-7,7,97:77T-77= 1. %%%% tttttttttttttt inn,

/9

To the sides of the aorta and in the points of origin

of the parietal arteries, between the lobules of medullar sub-

stance or near them, it is possible to see the odd small lobule

of cortical substance (Fig. 6, s.c., c.m.). On the other hand,

cortical substance is never found outside the area of the aorta

and the cardinal veins, and for this reason, it has never been 147/ 148

seen along the course of the dorsal and ventral ramifications of

the arteries and parietal veins.

- A couple of centimeters before reaching

the level of the anal opening, we pass to the region of the caudal

vein. Here, the two bands of chromaffin tissue, which ran along

the sides of the aorta, join together in such a way as to cover

the roof of the caudal vein with a layer of medullar substance,

which faces the vasal lumen and is covered on this side by the

endothelium, while on the opposite side, it thrusts itself into

the connective tissue situated between the caudal artery (aorta)

and the vein. This layer of medullar substance extends laterally

from the roof of the vein along the course of the parietal arte-

ries and their dorsal and ventral ramifications, as it did in the

preceding region (Fig. 2, c.m.).

The cortical substance, under the form of the usual lo-

bules, is distributed more particularly on the lateral and ven-

tral walls of the vein (Fig. 2, s.c.).

This holds true for a good part of the caudal region,

almost up to the rear extremity of it.

- In that region of the

trunk situated between the pericardium and the apex of the kid-

neys, and which for convenience 1 am calling prerenal or interme-

/10

diate reglon, we also find an arrangement similar to that des-

cribed for the medial region (renal), however, with the diffe-

rence that while here the number of lobules of cortical sub-

stance gradually diminishes, the thickness of the medullar sub-

stance increaes considerably, and in some sections, at the level

at which the parietal arteries originate, it becomes quite visi-

ble. 148- 149

Çmdinpregion. - From the intermediate region, moving

in the direction of the craflium, we pass to the

Here the two posterior cardinal veins open at almost the same

level into the vein sinus, and the medullar substance, which

previously ran along the sides of the aorta, is now deposited

on its ventral face, protruding into the lumen of the sinus.

On the right side, at about the half-way point in the space com-

prising the vein sinus, the celiac artery breaks away from the

aorta, and the medullar substance also surrounds this artery,

which crosses the sinus obliquely in a caudal-lateral direction.

In the cardiac region, the medullar substance is accumulated in

relatively large masses, sub-divided into small lobules, some

of which penetrate the wall of the aorta. Nerve cells between

the elements of the medullar substance are very scarce in number.

As we pass from the vein sinus to the jugular veins, the

medullar substance is again distributed for a short distance in

the lateral faces of the aorta.

genhalicornreçaFdiac region. - This region, because of

the connections of the medullar substance, could also be called

imullr. Beyond the cephalic kidneys, cortical substance is no

longer to be found, but only medullar substance, which follows

lo 4,7

/11

the course of the parietal arteries of the region, however, •

always facing the lumen of the jugular veins, against the wall

of which the ramifications of these arteries are pressed, in

such a way that the medullar substance now appears as a layer

of chromaffin cells, applied to the internal face of the jugu-

lar veins, in the tracts in which they are in contact with the

artereal ramifications (Fig. 5). Something which I feel is

worthy of note is that the elements of the medullar substance,

following the parietal artery branch, pass by the jugular Vein

laterally, until they arrive in the vicinity of the pneumogas-

tric region.

When they are about to open into the vein sinus, the

jugular veins run along the aorta, while they grow further and

further away from it as they advance into the branchial region

and consequently, there is no longer any trace of medullar sub-

stance to the sides of the aorta. On the other hand, however,

the presence of this substance along the jugular veins was clear-

ly observed by me right up to the level of the second pair of

fins.

2e2ahliç_kipineys. - In the cardiac region we find the

rudiments of the cephalic kidneys, which escaped the observa-

tions of Collinge and Vincent (4) who claimed that they were

absent.

Once the ventral segment of the cartilaginous pericar-

dium has been removed and the heart carefully detached, the bot- •

tom of the pericardiac cavity is uncovered, and in it, almost

on the median line, the vein sinus appears and to the left a

/12

cylatindrical projection, facing obliquely from front to back,

determined by the esophagus, which in this tract of its course

is displaced towards the left. In two crypts, one on the ante-

rior edge of the vein sinus, the other, which is deeper, to the

left side of the esophagus, the cephalic kidneys are lodged. 149/ 150

Of the two prokidneys, therefore, the right one is

situated almost transversely on the cranial margin of the vein

sinus, the left one, facing in a cranio-caudal oblique direction,

laterally in relation to the esophagous, which separates it from

the left lateral margin of the sinus. The two cephalic kidneys

are not connected with the posterior cardinal veins, since each

of them, as I have found from repeated observations, is located

ventrally with respect to the jugular vein on its own side, at

the level of its opening into the vein sinus.

In the adult, the pronephra are two mexxmot bodies of

small dimensions ( 3.5 mm. by 1.5 mm. approx.), which in the

fresh state have a pearlish-grey colour, almost translucid, in

that part which constitutes the nephrostomae, and a whitish-

porcellain colour in the other part which represents the glo-

merule and is situated medially in relation to the first. They

thus stand out from the base on which they rest and which is

generously strewn with blotches of pigment. The surface of the

glomerule is lobulated, while that corresponding to the region

of the nephrostomae is folded in various ways and wrinkled, with

umbilications due to the openings of the funnels into the peri-

cardiac cavity. A flagellated epithelium, of which the long,

flagella move quite vigourously, as may be easily observed feom

.,,,, . • ,,, . ,,

/13

the examination of fresh material, limits the dimensions of

the nephrostomae and covers them internally as they imbed

themselves in a connective tissue containing a large number

of lymphatic ducts and blood sinuses, these latter communica-

ting with the jugular vein. The funnels seem to open deeply

into the lymphatic sinuses. The glomerule still remains gene-

rously vascularized. The pericardiac cavity contains a small /150

quantity of clear, colourless liquid. It is plausible that

the rudimentary prokidneys now have the function of supplying

this liquid and at the saine time, regulating its quantity.

In the small masses to which the remnants of the pro-

kidneys are reduced, there is no longer any urine canal and

not even a trace of the pronephres canal.

But what I am most anxious to mention is that in the

mass representing the rudiments of the prokidney, in addition

to accumulations of lymphoid cells, we also find lobules of

cortical substance, similar to those spread over the walls of

the cardinal veins.

Petromyzon Planeri

After what I have expounded concerning the suprarenal

capsules of Petrom zon marinus, I need only a very few words

to summarize the arrangements observed in this regard in

Petromyzon Planer!. In this species, in fact, the conditions

are very similar to those found in the other, with the difference,

certainly not essential, that the lobules of cortical substance

are less numerous and smaller and the medullar substance is not

rn

150/ 151

..... ... ...

/14

so easy to discover, and forms quite thin layers, generally

composed of a single series of cells, and consequently, scarce-

ly visible in the entire post-cardiac region. In the cardiac

region, on the other hand, where its distribution is dmilar to

that already mentioned for P. marinus, the medullar substance

becomes more visible, in particular on the ventral face of the

aorta and around the celiac artery.

It is only through careful observation that it is pos-

sible to notice chromaffin cells in those tracts of the jugular

veins pressed against the ramifications of the parietal arteries

of the precardiac region.

Rudiments of the cephalic kidneys with nephrostomae and

with the glomerule are also present in Petrolmon_Planeri, and

both in their structure and in their connections, they are exact-

■ .

ly like those described in P. marinus although the lobules of

cortical substance which they contain attain sizeable dimensions

in comparison with others spread along the cardinal veins.

Ammocoetes

In Ammocoetes of 35. mm. in length, the smallest 1 have

been able to examine, there are already traces of the arrangements

which later develop in the adult. These arrangements become in-

creasingly more apparent with the growth of the larva, so that,

upon studying series of cross-sections of Ammocoetes about to be-

come transforined, it is in no way difficult to note the cortical

substance of the suprarenal capsules in the form of small lobules,

spread over the wall of the cardinal veins or on the ventral face

rt Ten",

/1 •

of the aorta. The medullar substance requires more careful

observation, xxd but is fairly visible to the sides of the

aorta, at the level of origin of the parietal arteries. Here

the medullar substance generally consists of a simple series

of cells, relatively large, epithelial in appearance and pro-

truding into the lumen of the cardinal vein, fr -Dm which they

are separated only by a very thin endothelial layer. Cells

which are similar but not so high, follow the course of the

parietal arteries, and also extend over the dorsal wall and 151/ 152

a certain portion of the lateral wall of the cardinal veins.

As we pass to the caudal region, it is easy to ob-

serve, more particularly in larvae in a fairly advanced stage

of development, that the roof of the caudal vein is covered

with a layer of medullar cells, dmilar to those found to the

sides of the aorta.

No less typical arrangements are found at the level

of the cardiac region. On the ventral face of the aorta, in

particular at the level of confluence of the jugular veins,

there is a thin layer of medullar cells (Chromaffin). Around

the celiac artery as we11, when this is already detached from

the fx dorsal side of the aorta, there are cells of medullar

substance, which accompany it for a goodly part of its journey.

It must also be noted that in the cardiac region, there are

lobules of cortical substance, preseed against the ventral face

of the aorta or against the celiac artery, and that sometimes

these are situated between or below the chromaffin cells, so

that it is not infrequent that lobules of cortical substance

/16

/hanging and elements of medullar substance are 4m±nzei together on the

wall of the aorta or of the couac artery, and that the first

are arranged in various ways in relation to the second, until

they come in contact with each other. But regardless of the

closeness of the connection between the two, it is never possi-

ble to confuse them, because their respective characteristics,

which are quite peculiar, always make it possible to distinguish

them, even quite apart from the membrane proper, which surrounds

the lobules of cortical substance. In any case, I exclude the

possibility that the first are derived from the second, since I

have never noted signs which would make such a transformation

seem probable, and this is true also as regards the connections

between the medullar substance and the cortical substance of the

suprarenal capsules of the adult.

Relatively large lobules of cortical substance are also

to be found in the cephalic kidneys of Ammocoetes.

In the cephalic kidneys of the younger larvae which I

examined, lobules or solid epithelial cordons may already be ob-

served between the urine canals, surrounded by their own membraneR

and enclosing cells of various shapes, cylindrico-prismatic or

otherwise polyhedral, or else tapered and pressed together, which

possess characteristics of their own, which differentiate them

from the elements of the renal canals and causes them to ressem-

ble rather those enclosed in the lobules of cortical substance

distributed along the cardinal veins.

Of these lobules contained in the pronephra, some are

located on the surface and others at a more or less deeper level.

/17

An examination of the series cuts demonstrates that they are

completely without a lumen and have no genetic relation with

the urine canals. On the other hand, the study of the cephalic

kidneys in consecutive larval stages up to the Ammocoetes about

to be transformed, demonstrates that the solid epithelial lo-

bules of which we are speaking, do not in any way serve to pro- 152/

vide urine canals, but retain their own particular characteris- 153/

tics; and that, while the canals of the prokidneys disappear

completely or almost in the advanced stages, the lobules remain

and finally reappear as lobules of cortical substance in the

rudimentary cephalic kidneys of the adult.

Having summarized the arrangements of the suprarenal

capsules of Ammocoetes, it is fitting that I compare my data

with those obtained by Julin (14 & 15) on the sympathetic ner-

vous system of Ammocoetes.

In the brief bibliographical notes found at the begin-

ning of my work, I made no mention of the fine thorough research

conducted by Julin on the Ammocoetes, for the simple reason that

in this research, there is absolutely no mention either of the

bodies described by Rathke, or of others comparable to supra-

renal capsules; but since I must say a few words about the con-

nections of the suprarenal capsules of the Petromyzonti, and

more particularly of their medullar substance, with the sympa-

thetic nervous system, it is fitting that I make mention here

of the conclusions arrived at by Julin in his study of this

system in the Ammocoetes.

, '

/18

We know that no one, prior to Julin, had demonstrated

the existence, in the Cyclostomi, of a sympathetic nervous system

comparable to that of higher Vertebrates.

Julin, concentrating his study on the sympathetic nervous

system of Ammocoetoes 15 to 18 cm in length, discovered the pre-

sence, to the left and to the right of the aorta, between it and

the cardinal veins, of small organs, generally rounded in shape,

situated at regular intervals, from the origin of the heart up 153/ 154

to a short distance before the orifice of the cloaca.

In these organs, he recognized the structure of nerve

gangue, and subsequently, what represented the ganglia of the

sypathetic nervous system, joined together by means of nerve

branches (visceral branches) with the ventral branches of the

spinal nerves. In addition, he noted the total absence in the

Ammocoptps of a sympathetic cordon joining all the ganglia on a

given side. In addition to these "superficial" sympathetic glun-

glia, according to Julin, there are others, located at a deeper

level (deep sympathetic ganglia), which are quite closely connected

to the first, and which are in much more direct fonnection with

the visceral organs.

Now I must say in parting that from my observations, car-

ried out not only on series cuts of Ammocoetes and PeImulon Pla-

iïeri, but also on numerous series of lenrx cross-sections of the

various regions of the trunk of Petromyzon marinus, I did not find

that these Cyclostomi have a sypathetic nervous system such as

that described by Julin. If the sympathetic ganglia seen, des-

cribed and uh5z7.tgiumit sketched by Julin in Ammocoetes, might have

/19

escaped my notice in the larvae and in Petromyzon Planeri, I do

not believe they would have done so in the large specimens of

petrommon_marings which I examined. Among the numerous sections

examined, I never came across even one in which I was able to

observe the sympathetic ganglia described by Julin as being on

the sides of the aorta. However, since the accuracy of Julin's mis

observations cannot be doubted, it is to be supposed that he took

for sympathetic ganglia the lobules of cortical substance of the

suprarenal capsules which, as I said, may be seen on the sides

of the aorta facing ventrally from it; and that in the same way,

he mistook for sympathetic ganglia the cells of medullar substance

reDresented in Ammocoetes, to the sides of the aorta'at the level

of origin of the parietal arteries, by small groups of cells, gene-

rally arranged in a simple layer, relatively large and protruding

into the lumen of the cardinal veins, from which they are separated

only by means of a very thin endothelial layer.

must confess, however, that there is one thing I am un-

able to explain: how did Julin see, in these small groups of cells,

the full structure of a real ganglion in the form of an A, sketched

in Fig. 6 of Table XXIII from memory, structure which I vas fully

unable to identify. T

Therefore, while denying the existence of an arrangement

of the sypathicus as described by Julin for Ammocoetes, I must

maintain that he was certainly led into error by appearances,

which now find a totally different explanation from the comparison

which may be made between them and the conditions found in adults

/20

of per_t_rommun marinus. Add to this that if my observations,

confirming on this point those of Freud (9), revealed the exis-

tence of gangliar cells along the course of the ventral branches

(and also, though less frequently, of the dorsal branches) of

the spinal nerves, they never served to convince me, even in

P. marinus, where, because of their size, it would have been

easy to note them, of the existence of visceral nerve branches

which extend from the ventral trunks of the spinal nerves to 154/ 155

those qccumulations of medullar cells distributed along the

sides of the aorta. I therefore insist, basing my opinion prin-

cipally on my research in P. marinus, that at least as regards

the sepathetic nervous system of the entire post-branchial re-

gion, or in other words, from the trunk to the tail, it does not

consist of ganglia to the sides of the aorta and visceral branches

(communicating branches) in such a way as to be comparable,

quite apart from the absence of a cordon of demarcation, to that

of higher Vertebrates. And to support this statement, I might

recall that even im the research of Ransom and Thompson (29),

shortly prior to that of Julin, did not serve to demonstrate the

existence, in the post-branchial region of Petrol-nun, either

of ganglia or of branches communicating with the sypathicus.

Therefore, without denying their existence, I believe

that the sympathetic nervous system of the Petromyzonti consists

of scattered gangliar cells or, less frequently, however, joined

together to form small ganglia, inside the wall of the body (1)

F-77-is understood that I am leaving aside the sympa-thicus of the viscera contained in the abdominal cavity, as well as the sympathicus of the intestine, etc., which, on the other hand, also consists of scattered gangliar cells.

/21

along both the ventral and dorsal branches of the spinal

nerves and the course of the ramifications of the arteries

and parietal veins. To the sides of the aorta, I have only

found the odd lone gangliar cell, and this only very rarely.

More numerous, but still scattered, are the gangliar cells in

the vicinity of the opening of the parietal veins into the

cardinal veins, as well as near the bifurcation of the parietal

arteries and along the course of the ventral branches of these

vessels. Sympathetic nerve cells are also to be found around

the cardinal veins. In the caudal region as well, I have seen

individual gangliar cells around the caudal vein and more espe-

cially on the dorsal side, near the layer of medullar substance.

However, in the caudal region, nerve cells are frequent and

quite visible, as well as a few small ganglia, along the ventral

nerve branches and near the ventral parietal vessels.

And with these findings, I am in agreement with Prof.

Dohrn (7), who found the sympathicus in Petromyzon to the rear

extremity of the trunk under the form of scattered gangliar cells,

except that instead of limiting this system to the rear extre-

mity of the trunk, I would extend it not only to the entire

trunk, but to the caudal region as well. For which reason,

I would be 'inclined to am maintain that these scattered sympa-

thetic gangliar cells, rather than being a residue of the sympa-

thetic nervous system in these Vertebrates, as Dohrn claims,

are an initial manifestation of this system. As for the phylo-

genesis of it, it seems to me more priobable that it first began

appearing in the form of individual sympathetic neurons, which

/22

became detached from the material of the spinal ganglia, and

which only later became more concentrated and developped to

the point of assuming a definite shape.

Julin saw a primitive arrangement in those series of

ganglia, not joined together by means of a limiting cordon, 155/ 156

which he believed were present on the sides of the aorta, but

since it has now been established from my research that those

groups of cells are not sympathetic ganglia, I would, on the

other hand, consider as a primitive arrangement that of the

sympathicus not yet accumulated in ganglia located to the sides

of the aorta (1).

Some of the sympathetic gangliar cells scattered in this

manner along the aorta, the cardinal and caudal veins, or along

the ramifications of the parietal veins are, as has already been

pointed out, more or less closely connected with the groups of

cells of medullar substance of the suprarenal capsules.

(1) It is quite true that in the Cyclostomi and in our case, in the Petromyzonti, Vettebrates which are not considered as primitively simple, but rather partially degenerated, it is quite difficult to determine whe-ther certain arrangements found there must or must not be considered as truly primitive, but ineany event, it does not seem to me that one shoulenmpletely deny their morphological importance, especially if we con-sider a well-founded concept expressed by Grassi (13) concerning the value of simplified or degenerated animal forms, that, i.e. these forms "on the one hand retain characteristics which have been at least par-tially lost in other forms of the group. On the other hand, they may repeat the conditions present in their ancestors at the origin.''

/23

The main conclusion to be drawn from the findings of

my research may be summarized essentially as follows: that the

Petromyzonti have two very distinct series of special organs of

secretion (glandular-shaped organs) which secrete internally

(endocrine), and which extend almost along the entire body,

comparable in their overall structure to the suprarenal cap-

sules of the Gnatosthoma.

The comparison assumes greater value when the arrange-

ments found in Petromyzon are compared with those already noted

in the Selachii and Amphibia. Of these two weries of organs,

one corresponds to the cortical substance or cortex (cortex of

the Stapedipherous3 suprarenal body of the Selachii).

These organs are not closely connected with the excre-

tory system, as is demonstrated by the fact that they extend to

regions of the body (branchial and caudal region), which the

exèretory system never reaches. This fact, assuming the accu-

racy of my interpretation of the above comparison, in which one

series of special organs found in the Petromyzonti is likened

to the interrenal body of the Selachii and the cortical substance

of the suprarenal capsules of the higher Vertebrates, the other

series w±±11 to the suprarenal bodies of the Selachii and the

medullary substance of the suprarenal capsules of the higher

Vertebrates, this fact, I repeat, is in clear contradiction

with the views of Aichel (1), who claims that both substances

comprising the suprarenal capsules are derived from a primitive

kidney. The findings of my research are also in contradiction

with the new homology which the same Aichel, contrary to what

/24

was previously observed by Leydig and Balfour, later confirmed

and more fully demonstrated by Diamare (6), Vincent (32, 33)

and in part by myself (10, 12), tries to establish between the

interrenal body of the Selachii and the suprarenal capsules of

the higher Vertebrates on the one hand, and on the other, be-

tween similar suprarenal bodies of the Selachii and certain

bodies (accessory suprarenal capsules or Marchand's suprarenal

capsules, as Aichel calls them) which nm are normally present /157

in Mamals in relation to the genital organs, in the ligamentum

latum of the female, and near the testicle and sperm cordon in

the male.

The particular arrangement of the suprarenal capsules

in the Petromyzonti would lead us to believe that the system of

these organs is completely independant of the excretory system,

with which it perhaps assumes only secondary connections.

Therefore, we should do away with the designations

suprarenal capsules, cortical substance and medullar substance,

which is what will certainly come to pass, once more precise

knowledge concerning their respective functions permits us to .

replace the old terminology with a new,more appropriate one.

The arrangement of the medullar substance, as it occurs

in the Petromyzonti, probably represents a primitive condition (1)

but even if this were not the case, this is still a better ex-

planation of that occurring in the Elasmobranchii and of the pre-

sence of nests of cells (chromaffin cells) in the ganglia and

(1) See note on previous page

/2 5

nerve ends of the abdominal sympathicus of the Amphibia and

higher Vertebrates, in the ganglia of the cervical sympathicus

and the intercarotic gland of Mammals and man. It can also

give us some knowledge' of the formation and structure of the

coccygeal gland, in connection with which, after seeing that the

medullar substance also extends to the caudal region, it will

not be surprising if, as Vincent previously suggested (38 & 39),

chromaffin cells are to be found.

A fact which deserves particular consideration is that

in the Petromyzonti, the tissue of the medullar substance

largely predominates over that of the sympathetic nervous sys-

tem, with which it may be connected, nimmx±lue so that the

groups of cells of medullar substance, such as we see them in

the Petromyzonti, can hardly be designated as paraganglia, term

which Kohn, following his own personal concept, proposes as a

name for the suprarenal bodies of the Selachii, the nests of

chromaffin cells and the medullar substance of the suprarenal

capsules of the higher Vertebrates (paraganglion of the supra-

renal capsules), reserving the name of suprarenal capsules

strictly for the cortical substance.

Kohn (16, 17, 18) denies that the chromaffin cells, and

consequently, the suprarenal bodies of the Selachii, are of a

glandular nature as claimed by Vincent (32 & 33) and by myself

(10 & 12); he further denies that the parenchymal elements of

these bodies and those of the cellular nests in the ganglia of

the sympathicus are epithelial, secreting elements, as I main-

tained they were after studying them in the Amphibia, and re-

gards them instead as special nerve elements.

,

/26

The cells comprising the medullar substance of the suprarenal

capsules of all Stapedipherous (î) are to be considered in

the sanie light. Now my observations of the structure and ar-

rangement of the medullar substance in the Petromyzonti, rather

than leading me to abandon the opinion already expressed pre-

viously, only serve to confirm it in my mind, since in truth

I would find it impossible to recognize the characteristics of

a nerve tissue in those layers of cells distributed along the

sides of the aorta, along the parietal walls, constantly facing

the lumen of the satellite veins and separated from it only by

means of the very thin endothelial layer. In my opinion, these

relations as well serve to indicate the excretory nature of the

tissue representing the medullar substance, so that I am even

more inclined to doubt that the nests of cells can be regarded,

with Kohn, as masses of special nerve elements.

And I say this basing my opinion solely on structural

appearances, for if we do not wish to discredit the value of

the physiological experiments of Vincent and others, which tend

to demonstrate that the parenchymal elements of the suprarenal

bodies and of the medulla of the suprarenal capsules contain an

active substance with a truly extraordinary capacity for raising

blood pressure, then the doubt can only grow.

The fact of finding medullar substance distributed along

the course of the dorsal branches of the arteries and parietal

veins, up until just beyong the spinal ganglia, could be consi-

dered as an indication of the route followed by elements of this

substance before becoming more deeply lodged, and could be

/27

regarded as evidence supporting the theory that it is derived

from the nervous system (from the sympathicus) and that, in the

final analysis, it is of ectodermal origine

Although new facts have been brought to light by Kohn

(17 & 18) and more recently by Diamare (6) supporting the /159

theory of the derivation of the nests of cells and of the

suprarenal capsules from the sympathicus, revealing inter-

mediate forms between nerve cells and chromaffin cells, I, how-

ever, on the basis of what I have observed in the Petromyzonti,

cannot say I have reached the same conclusion. At the most,

from what I have observed in Petromyzonti, it may be assumed

that if sympathetic ganglier cells and chromaffin cells (medul-

lar cells) originate from the same primitive material, they

later follow two different routes, developping in their Gun

fashion. Which would confirm the idea expressed by Diamare (6)

"that elements originating from the ganglia (in an initial

stage of development) do not reach the stage of gangliar bodies."

Idea which seems to gibe in part with the opinion I myself ex-

pressed in preceding notes, when I maintained that, even admit-

ting the derivation of the medullar cells from the sympathicus,

they do not present the characteristics of nerve cells but

rather those of epithelial and excretory elements (10, 11 & 12).

must, however, admit more reservations concerning the

opinion expressed above to the effect that the distribution of

the medullar substance in the lateral-dorsal walls of the body

of adult Petromyzonti, indicates the road it originally tra-

velled, since I expected, in support of my theory, to find that

/28

in young Ammocoetes, the medullar substance was more clearly

visible in the vicinity of the spinal ganglia or in the lateral-

dorsal wall of the body than to the sides of the aorta, and on

the contrary, I clearly observed, in the smallest emmocoetes 159/ 160

examined (35 mm. in length), medullar cells between the lateral

wall of the aorta and the endothelium of the cardinal veins,

in the vicinity of the origin of the parietal arteries, but

not, however, along the dorsal branch of these arteries or near

the spinal ganglia. Further research is therefore necessary on

this point, as well as the examination of more primitive stages,

before a final judgement can be expressed.

But if some doubt remains in my mind as to the origin

of the medullar substance in the Petromyzonti, without, on the

other hand, excluding a priori its derivation from the ectoderm

(from ectodermal material of the nervous system), I also have

doubts as to the origin of the cortical substance. It is known

that with regard to the origin of this substance in the higher

Vertebrates, there is still much uncertainty, since some claim

it derives from the mesenchyma and others that it derives from

the celomatic epithelium or the epithelium of the genttal crest,

still others that it derives from the epithelium of the capsule

of the malpighian glomerules, or from the nephrostoma and urine

canals of the prokidney or primitive kidney.

I wish to say in parting that, not having made direct

observations or obtained actual evidence, I am merely following

a process of deduction in my reasoning.

Without touching on the origin of the lobules of cortical

substance found in the region of the cephalic kidneys and the

J

/29

others located along the aorta and the cardinal veins, with

regard to which, I have already remarked that I am inclined

to exclude any genetic relation with excretory apparatus and

I might add, with greater reason, to the epithelium of the

genital crest; I shall only discuss the origin of those lo-

bules of cortical substance situated around the caudal vein

in the Fetromyzonti. Without any doubt, it seems to me that

for them, one must exclude any origin from the excretory appa-

ratus or from the epithelium of the genital crest, since it

would be really useless to look for a similar connection. It

might, however, be supposed that they repeated their origin,

in a very early stage of development, from the celomatic epi-

thelium which covers the rear extremity of the visceral cavi-

ty. But against this supposition, there is the fact of their

tardive appearance. And in fact, from my observations on

Ammocoetes, it would seem that they appear relatively late /with

and in points in which the celomatic navity no longer has any

connection.

Since their direct origin from the celomatic epithelium

does not seem probable, we can only assume that they are de-

rived from the mesenchyma or from a differentiation of cells of

the perivasal connective tissue.

Now if, as I maintain, the lobules of cortical substance

situated around the caudal vein and the other spots along the

cardinal veins and in the region of the prokidney are homolo-

gous, unless we wish to assume a different origin for each of

them, we must necessarily come to the conclusion that all the

• •••• • •• .... ..... ••• ■ •••• ■ ••• ..... •••• ■-• ...... • ... -.:••••••••••••••• ..... • .. ,•-•.-•,,,,r,r,...,..-1-•-r"-^,••••••••••-••,•••›•••••••,••• ■ •

1

/30

lobules of cortical substance of the suprarenal capsules of

the Petromyzonti find their origin the the mesenchyma or in the

perivasal connective tissue of the vein vessels, around which

they are located. But, as I have stated, not having evidence

and direct observations carried out, I do not dare affirm that

this is what actually occurs, so much more so since, in reaching

this conclusion, ± we would create strong contradiction between

the clearly epithelial nature of the lobules of cortical substance

and their origin from an embryo (mesenchyma) which does not have

an epithelial structure (as have the mesoderm and the mesothe-

lium) and from which we are not accustomed to seeing organs ori-

ginate which are definitely epithelial in character.

I have merely expounded thoughts and expressed doubts,

since it seems to me that at the present state of our knowledge

concerning Lho origin ,-)f the parts comprising the suprarenal

capsules (cortex and medulla) in the Cyclostomi and in the Gnatao-

sthOma, we are still without reliable data.

`7,77'7..7777 1 ,171,-,

BIBLIOGRAPHY

(1) Aichel, O. Vergleichende Entwicklungsgeschichte und Stammes-

geschichte der Nebennieren. Heber ein neues normales Organ des

Menschen und der Sâugethiere. Arch. far mik. Anat. Bd. 56. 1900.

(Comparative biogeny and phylogeny of the suprarenal glands. On

a new normal organ of man and mammals.)

(2) Balfour, F.M. Ueber die Entwicklung und die Morphologie der

Suprarena1k8rper (Nebennieren). Biolog. Centralbl., 1881. (On

the development and morphology of suprarenal bodies (suprarenal

glands).

(3) A monograph on the development of elasmobranch Fishes. London 1878.

(4) Collinge, W.E. and Vincent, S.W. - On the so-called suprarenal

bodies in Cyclostomata. Anat. Anz. Bd. XII, pag. 232-244. 1896.

(5) Diamare, V. - Ricerche intorno alltorgano interrenale dei Elasmo-

branchi ed ai corpuscoli di Stannius dei Teleostei, contributo alla

morfologia delle capsule surrenali. Mem. di mat. e di fis. della

Società Italiana delle scienze. S. 3, T. 10. (Research on the inter-

renal organ of the Elasmobranchii and the corpuscles of Stannius

in Teleosts, contribution to the morphology of suprarenal capsules.)

(6) Sulla costituzione dei gangli simpatici negli Elasmobranchi e sulla

morfologia dei nidi cellulari del simpatico in generale. Anat. Anz.

Bd. XX, No. 17, 1902. (On the structure of sympathetic ganglia in

the Elasmobranchii and the morphology of cellular nests of the

sympathicus in general).

(7) Dohrn, A. - Studien zur Urgeschichte des WirbelthierMrper IX.

Mittheilungen aus der zool. Station zu Neapel. (Studies on the

primeval history of Vettebrate bodies)

(8) Ecker, Al. - Der feinere Bau der Nebennieren beim Menschen under

den vier Wirbelthierklassen. Braunschweig 1846. (The fine structure

of suprarenal glands in man and in the four classes of mammals).

(9) Freud, S. - Ueber Spinalganglien und Rackenmark des Petromyzon.

Sitzungsberichte der kais. Akad. der Wiesensch. Wien 1879. (On

the spinal ganglia and spinal cord of the Petromyzon).

(10) Giacomini, E. - Sopra la fina struttura delle capsule surrenali

degli Anfibii. Estr. dai Processi verbali della R. Accad. dei

-2- ()

Fisiocritici, S. IV, Vol. X. Siena 1898. (On the fine structure

of the suprarenal capsules of Amphibia).

(11) Sulle terminazioni nervose nelle capsule surrenàli degli Uccelli.

Ibid. November 24, 1897. Siena 1898. (On the nerve ends in the

suprarenal capsules of Birds. Ibid. November 24, 1897. Siena 1898.

(12)Brevi osservazioni intorno alla minuta struttura del corpo inter-renale e dei corpi soprarenali dei Selaci. Atti dell R. Accad. dei Fisiocritici, S. IV, Vol. X. Siena 1898. (Brief observations

on the fine structure of the interrenal body and the suprarenal

bodies of the Selachii).

(13) Grass!, B. - Metodi e fini della morfologia. Estr. dal Supple-

mento al Policlinico. 1896. Rome 1896. (Methods and purposes

of morphology).

(14) Julin, Ch. - Recherches sur l'appareil vasculaire et le système nerveux periphérique de l'Ammocoetes (Petromyzon Planeri). Arch.

de Biologie. Tome VII. 1887 (Research on the vascular apparatus

and the peripheral nervous system of the Ammocoetes)

(15) Le système nerveux grand sympatique de l'Ammocoetes (Petromyzon Planeri). Anat. Anz. II, 1887. (The sympathetic nervous system of the Ammocoetes).

(16) Kohn, A. - Ueber die Nebenniere. Prager med. Wochenschr. 1898 (On suprarenal glands).

(17) Die Nebenniere der Selachier nebst Beitrngen zur Kenntniss der

Morphologie der Wirbelthiernebenniere im Allgemeinen. Arch. nil' mik. Anat. Bd. 53, 1898. (The suprarenal glands of the Selachii

kIaà with contributions to the knowledge of the morphology of supra-

renal glands in mammals in general).

(18) Die chromaffinen Zellen des Sympathicus. Anat. Anz. Bd. 15, 1889 (The chromaffin cells of the sympathicus).

(19)Ueber den Bau und die Entwicklung der sog. Caratisdr"use. Arch. far mik. Anat. Bd. 56, 1900. (On the structure and development of the so-called carotid gland)

• !

(20) Leydig, F. - Beitrgge zur mikroscopischen Anatomie der Rochen und Haie. Leipzig 1852 (Contribution to the microscopic anatomy of rays and sharks)

-3-

(21)Anatomishce-histologishe Untersuchungen dber Fische und Rep-

tilien. Berlin 1853. (Anatomical-histoloecal studies

of fish and reptiles)

(22) Lehrbuch der Histologie des Menschen und der Thiere. Frankfurt

a M. 1857. (Compendium on the histology of man and beasts)

(23) Die in Deutschland lebenden Arten der Sauner. Tdbingen 1872. (Types of saurians native to Germany)

(24)Moore, B. and Vincent, S.W. - On the comparative chemistry of

the suprarenal capsules. Proc. Roy. Soc. London, Vol. 62.

(251 Further observations upon the comparative chemistry of the suprarenal capsules, etc. Ibid. Vol. 62.

(26)Mailer, J. - Vergleichende Anatomie der Myxinoiden. Berlin

1834-1845 (Comparative anatomy of the Myxinoids)

(27)M iller, W. - Das Urogenitalsystem des Amphioxus und der Cyclo-

stomen. Jenaisch Zeitschr. fdr Naturwiss. 9 Bd. Neue Folge, 2 Bd. p. 94-129. Jena 1875. (The urogenital system of the Amphioxus and the Cyclostomi)

(28)Pett4, A. - Recherches sur les capsules surrenales. Journal

de l'Anat. et de la Phys. Année 32. Paris 1896 (Research on

suprarenal capsules).

(29)Ransom, W.B. and Tompson, W. D'Arcy - On the spinal and visceral nerves of Cyclostomata. Zool. Anz. IX. 1886.

(30)Rathke, H. - Beitrdge zur Geschichte der Thierwelt. Abt. 4 Halle 1827. (Contribution to the history of fauna)

(31)Retzius, A. - Beitrag zu der Anatomie des Aderund Nervensystem der Myxine glutinosa. Arch. f. Anat. und Phys. 1826. (Contri-bution to the knowledge of the anatomy of the vein and nervous system of the Myxine glutinosa)

(32) Vincent, W. - Contributions to the comparative anatomy and histology of the suprarenal capsules. The suprarenal bodies in Fishes, and their relation to the so-called head-kidney.

(33) The suprarenal capsules in the lower vertebrates. Proceed. of the Birmingham natural hist. and phil. Soc. Vol. 10. 1896.

•

, e -4-

(3 ) f ) On the morphology and physiology of the suprarenal capsules in Fishes. Anat. Anz. Bd. 13. 1897.

(3 • ) On the suprarenal capsules and the lymphoid tissue of teleostean Fishes. Anat. Anz. Bd. 14. 1897.

(36) The comparative physiology of the suprarenal capsules. Proc. Roy. Soc. London. Vol. 61. 1897.

(37)Further observations upon the comparative physiology of the suprarenal capsules. Ibid. Vol. 62.

(38) The comparative histology of the suprarenal capsules. Internat. Monatschr. f. Anat. und Phys. Bd. 15. 1898.

(39) The carotid gland of Mammalia and its relation to the suprarenal capsule, with some remarks upon internal secretion, and the phylogeny of the latter organ. Anat. Anz., XVIII, 1900.

(40)Weldon, W. - On the head kidney of Bdellostoma with a suggestion as to the origin of the suprarenal bodies. Stud. from the morph. laboratory in the Univ. of Cambridge. Vol. IL Part. I. 1884. • Quart. Journ. of microscop. science. N.S. Vol. XXIV London 1884.

(41) On the suprarenal bodies of Vertebrata. Ibid. N.S., Vol. XXV London 1885.

4,1 •

== =Tr: 1'11 . 1 .......

EXPLANATION OF THE FIGURES

Contained in Tables II-III

All figures were designed with the Abbe camera lucida

Fig. 1 - Diagram and reconstruction of some cross-vertical sections

of the medial region of the trunk (kidney region). Enlargement:

about 11 diam.

Cede spinal cord; m.s. spinal medulla; a.p. spinal arch; r. kidneys;

s.v.s. suprarenal vein sinuses; ao., aorta; v.c. venae cavae (cardi-

nal veins); ap. parietal artery; a.p.d. dorsal parietal artery (dor-

sal ramification of the parietal art.); a.p.v., ventral parietal

artery (dorsal branch of the parietal vein); v.p.v. ventral parietal

vein (ventral branch of the parietal vein); c.m. 5 layer of medullar

cells, medullar substance of the suprarenal capsules; s.c. lobules

of cortical substance of the suprarenal capsules.

Fig. 2 - Diagram. From a cross-vertical section of the caudal region,

a short distance behind the anal opening. Enlargement: about 15 diam.

a.ca ., caudal artery (aorta); v. ca., caudal vein. All other abbre-

viations as in preceding figure.

Fig. 3 - Three lobules of cortical substance, s.c., designed from

a cross-section corresponding to the rear portion of the kidney

region. The lobules designed xxx were located on the lateral wall

of one of the cardinal veins e v.c., indicates the lumen of the vein,

towards which the lobules protrude, covered by the endothelium.

n.e., nuclei of the vasal endothelium. Enlargement about 215 diam.

Fig. 4 - Taken from a frontal section corresponding to the medial

or renal region. The figures rexpresents a tract of ventral parietal

vein (satellite of the vental ramification of a parietal artery), and

v.p.v. indicates the side of the lumen. In the wall of the vein

t -42-e

a layer of medullar cells, c.m. 5 protruding into the lumen and sepa-

rated from it by means of the endothelial layer only. n.e. nuclei

of the endothelium. Near the medullar cells, in c.g.s., a sympathe-

tic gangliar cell. c.p. pigmented cell. p.a.p.v. wall of the ventral

parietal artery. Enlarg. about 400 diam.

Fig. 5 - Taken from a cross-section of the cephalic region (precar-

diac or jugular). Represents a thin layer of medullar cells, c.m.,

separated from the lumen of the jugular vein, v.g., m by means of

the endothelium, of which the nuclei are seen in n.e. c.p. pignmented

cell. Enlarg. about 400 diam.

Fig. 6 - Taken from a cross-section in the medial or renal region.

Represents a lobule of cortical substance, s.c., and a group of

medullar cells, c.m., to the side of the aorta, between it and the

lumen of the cardinal vein. In the case shown the two substances,

cortical and medullar, are adjacent. Fixation with Flemming liquid;

coloring with gentian violet according to the iodochromic method of

Bizzozero. The black patches in the cytoplasm of the cells of corti-

cal substance represents drops of the fatty substance contained in

it. Enlarg. about 560 diam.

,,,,, ...... ....... ...... .... ....