Endocrine Rachel Boggus [email protected]. 10/19/2015Template copyright 2005 Endocrine...

Endocrine

Rachel Boggus

[email protected]

mailto:[email protected]

04/21/23 Template copyright 2005 www.brainybetty.com 2

Endocrine Secretion

• What is it?

• What is a feature common to endocrine tissues?

• Where are endocrine cells found?


Endocrine Secretion• What is it?

• Secretion of chemical messengers (hormones) directly into the blood stream to act on distant tissues

• What is a feature common to endocrine tissues?• Usually highly vascular to facilitate rapid dissemination of

secretory products• Where are endocrine cells found?

• Dispersed as single cells in epithelial tissues (gut and respiratory tract)

• As discrete clusters in another organ (pancreas, ovary, testis)

• Gathered in one specialized organ (pituitary, thyroid, parathyroid, adrenal, pineal glands)


The Pituitary gland

• What is the other name for it?

• What are the two parts of it?

• Where are each of the parts derived?

• What does each part consist of?


The Pituitary gland• What is the other name for it?

• hypophysis• What are the two parts of it?

• Adenohypophysis and neurohypophysis• Where are each of the parts derived?

• Adeno—from oral ectoderm, neuro—from neural ectoderm

• What does each part consist of?• Adeno—pars distalis, pars tuberalis, and pars

intermedia• Neuro—pars nervosa and infundibulum


Adenohypophysis

• What are the cell types in the adenohypophysis?

• How are the major cell types classified?


Adenohypophysis

• What are the cell types in the adenohypophysis?

• Acidophils and Basophils, Chromophobes, Folliculostellate cells

• How are the major cell types classified?

• Based on affinity of dyes for granules


Acidophils

• Stain pink in H&E, PAS

• What are the two types of acidophils and their products?


Acidophils

• Stain pink in H&E, PAS

• What are the two types of acidophils and their products? (remember the Ms)

• Somatotrophs—growth hormone—stimulate growth, RNA and protein synthesis, synthesis of somatomedins stimulate growth of long bones

• Mammotrophs—Prolactin—stimulates milk synthesis from the nips


Basophils

• Stain poorly with H&E, PAS

• What are the cell types and their products


Basophils• Stain poorly with H&E, PAS• What are the cell types and their products

• Thyrotrophs—thyroid stimulating hormone—stims thyroid hormone syn & secretion

• Gonadotrophs—Follicle stimulating hormone—promotes ovarian follicle development and estrogen secretion in females and spermatogenesis in males, Lutenizing Hormone—stims ovarian follicle maturation and progesterone secretion in females, stimulates leydig cells to secrete androgens in males

• Corticotrophs (POMC)—Post trans processing of POMC Adrenocorticotropic hormone (ACTH) Lipotropic Hormone, Melanocyte stimulating hormone, B-endorphin


Chromophobes & Folliculostellate Cells

• Chromophobes—few or no granules, no affinity for stain– What are they?

• Folliculostellate cells—supportive cells– What do they look like?


Chromophobes & Folliculostellate Cells

• Chromophobes—few or now granules, no affinity for stain– What are they?

–Degranulated secretory cells, undifferentiated secretory cells

• Folliculostellate cells—supportive cells– What do they look like?

–Appear stellate and extend branching processes among secretory cells, and are GFAP +


Pituitary – note vascularity of distalis


Pars intermedia

• What does it develop from?

• What does it contain?

• Note that fluid can accumulate giving rise to a cyst


Pars intermedia

• What does it develop from?

• The dorsal portion of Rathke’s pouch

• What does it contain?

• Mostly basophils and a few chromophobes

• Note that fluid can accumulate giving rise to a cyst


Pituitary Vascular Supply

• YOU MUST KNOW THIS!

• It shows you just how much control the hypothalamus has on adenohypophyseal (i.e. pituitary) secretion


Pituitary vascular supply (cont)

• Superior hypophyseal arteriesprimary capillary plexus irrigating median eminance and the stalk

• Small veins (portal) from primary plexus form secondary capillary plexus in adenohypophysis

• Why is the portal system important?


Pituitary vascular supply (cont)

• Why is the portal system important?

• For the delivery of concentrated releasing and inhibiting hormones from median eminance (where 1st cap. Plexus is) to adenohypophysis (where 2nd cap plexus is)


• Inferior hypophyseal arteries provide blood to neurohypophysis and the stalk

• THERE IS NO DIRECT ARTERIAL SUPPLY TO THE ADENOHYPOPHYSIS – this will be on your test!!!


Neurohypophysis

• What does it consist of?


Neurohypophysis

• What does it consist of?

• Unmyelinated axons of supraoptic and paraventricular neurons from hypothalamus

• Neurosecretory material (herring bodies)

• Pituicytes (highly branched glial [i.e. supportive] cells)

• Rich capillary plexus


Products of Neurohypophysis

• ***** NOTHING!!!!******– This will be on your test too!

• How is that possible?


Products of Neurohypophysis

• ***** NOTHING!!!!*******

• How is that possible?

• Vasopressin (ADH) and oxytocin are only STORED in the neurohypophysis but are MADE in the hypothalamus!

• What do these two hormones do?

• ADH—stims reabsorption of water

• Oxytocin stimulates milk let down


Neurohypophysis


The Thyroid gland

• What does it produce?

• What do these hormones do?


The Thyroid gland

• What does it produce?

• Thyroid hormones T3 and T4

• What do these hormones do?

• Regulate mitochondrial respiration, I.e regulate basal metabolic rate


Structure

• Slips from thin fibroelastic capsule divide it into lobules

• Lobules consist of follicles– What do follicles consist of?


Structure

• Slips from thin fibroelastic capsule divide it into lobules

• Lobules consist of follicles– What do follicles consist of?

–Simple cuboidal epithelial cells called principal cells that secrete thyroglobulin into center

–Thyroglobulin is stored as colloid EXTRACELLULARY

–This will be on your test too!!!!!!


THYROID


Principle cells

• What are their features?


Principle cells

• What are their features?

• Rest on basal lamina, apices point to center of follicle

• Typical apical junctional complexes (what are the three components?), short microvilli, well-developed supranuclear golgi, numerous RER, abundant lysosomes, mitochondria, and multivesicular bodies


Thyroid Hormone Synthesis

• Where is thyroglobulin synthesized? Modified? Released?

• How is iodide taken up?

• What happens to it once it is in the cell?

• What happens once it leaves the cell?

• What happens upon TSH stimulation?


Thyroid Hormone Synthesis• Where is thyroglobulin synthesized? Modified?

Released?• RER. RER and Golgi (carbs added). apical surface

via vesicles• How is iodide taken up?

• Iodide pump at basal membrane• What happens once it leaves the cell?

• Covalently bound to tyrosyl residues of thyroglobulin at apical memb by thyroid peroxidase

• What happens upon TSH stimulation?• Principal cell takes up colloid via pinocytosis and

releases iodinated tyrosines via lysosomal-derived protease activity


Parafollicular cells

• Where are they?

• What are they?


Parafollicular cells

• Where are they?

• Within follicular epithelium scattered in CT among follicles

• What are they?

• Produce calcitonin—lowers blood calcium levels; calcitonin keeps the Ca in (the bones, that is)

• Lots of RER and large Golgi


Parathyroid Gland

• What do they look like microscopically?

• What are the two cell types?


Parathyroid Gland

• What do they look like microscopically?

• Septa from capsule separate gland into lobules of dense anastomosing cords of cells


• Chief and oxyphil


Chief Cells

• What do they secrete? What does it do?

• What do they look like in LM and EM?


Chief Cells

• What do they secrete? What does it do?

• Parathyroid Hormone, increases blood calcium concentration

• What do they look like in LM and EM?

• LM—sm, centrally located nuclei in pale cytoplasm

• EM—mod. RER and Golgi, lots of glycogen, sm. Dense granules


Oxyphil

• What do they do?

• What do they look like?


Oxyphil


• Not sure but they contain PTH

• What do they look like?

• Larger than chief cells but nuclei smaller and more heterochromatin (what does that mean)

• Very eosinophilic cytoplasm (MITOCHODRIA), small RER, golgi and few granules


The Adrenal Gland

• What is the cortex derived from?

• What is the medulla derived from?


The Adrenal Gland

• What is the cortex derived from?

• Intermediate mesoderm

• What is the medulla derived from?

• Neural crest


Cortex

• What are the three zones of the cortex?

• What do the cells do?

• What are the features of the cells?


Cortex

• What are the three zones of the cortex?

• Zona glomerulosa, zona fasciculata, zona reticularis

• What do the cells do?

• Synthesize and secrete (but DON’T store) steroid hormones

• What are the features of the cells?

• Numerous lipid droplets, abundant smooth ER and mitochondria with TUBULAR CRISTAE


Zona Fasciculata & Reticularis

• (75% of cortex)

• What do they secrete?


• What is secretion regulated by?


Zona Fasciculata & Reticularis

• (75% of cortex)

• What do they secrete?

• Glucocorticoids cortisol and corticosterone


• Promote natural metabolism, esp. carb metabolism. Also provide resistance to stress and supress inflammatory response


• ACTH – from POMC REMEMBER????


Zona Glomerulosa

• What does it secrete?

• What is the function?



Zona Glomerulosa

• What does it secrete?

• Mineralocorticoids (aldosterone)

• What is the function?

• Maintaining normal mineral balance and body fluid volume


• Renin-angiotensin system and plasma levels of sodium and potassium


Adrenal


Blood Supply to the Adrenal Gland

• What gives rise to the subcapsular plexus?

• What does the subcapsular plexus give rise to?


Blood Supply to the Adrenal Gland

• What gives rise to the subcapsular plexus?• Superior, middle and inferior suprarenal arteries

• What does the subcapsular plexus give rise to?

1. Arterioles supplying capsule

2. Arterioles of the cortexsinusoidal vessels running between columns of fasciculata before forming deep plexus in reticularis that communicates with plexus in medulla

3. Arterioles that directly supply the medulla and forms medullary sinusoidal plexus


Venous Drainage

• Venous channels drain medullary plexus and empty into medullary vein– Has longitudinally oriented smooth muscles

– Thought to act as a gate regulating entry of blood from the reticularis and medullary sinusoidal plexus


Fetal Adrenal Cortex

• What are the zones?



Fetal Adrenal Cortex

• What are the zones?

• Fetal/provisional zone and definitive zone


• Fetal zone degenerates rapidly after birth

• Produces inactive androgens that are converted to active in the placenta and enter maternal circulation

• Definitive zone differentiates into adult cortex


Medulla

• What are cell types present?

• What is the vascular supply like?


Medulla

• What are cell types present?

• Chromaffin cells in clumps or cords

• Few ganglion

• What is the vascular supply like?

• Dilated capillary network surrounding medullary secretory cells and drain into medullary vein


Chromaffin Cell

• What does it contain, what do they do?

• What causes release?


Chromaffin Cell

• What does it contain, what do they do?

• Membrane-limited secretory granules

• Contain catecholemines (epinephrine, norepinephrine)

• What causes release?

• Released upon stimulation of preganglionic sympathetic neurons in response to intense emotional reactions


http://w3.uokhsc.edu/histology/Glass%20slides/39_09.jpg


Pineal Gland

• CT septa originate in pia mater and separate gland into irregular lobes


• What are concretions?


Pineal Gland• CT septa originate in pia mater and separate gland

into irregular lobes• What are the two cell types?

• Pinealocytes—slight basophilic cyto, irregular nuclei, long tortuous processes

• Astroglial—more basophilic lots of intermediate filaments

• What are concretions?• Corpora aremacea (brain sand) made of

calcium phosphate or calcium carbonate and indicate the secretory activity of the gland


Pineal Gland

• What do pinealocytes secrete? How is it regulated?


Pineal Gland

• What do pinealocytes secrete? How is it regulated?

• Melatonin

• Diurnal cycle under control of sympathetic division of ANS. Specifically entrained by light. More light less melatonin release.


Melatonin Secretion

• Why is it important in humans?


Melatonin Secretion

• Why is it important in humans?

• Possible antigonadal effect

• Size of pineal decreases after puberty

• Exogenous melatonin appears to help some people as a sleep inducer.

Image Review


Pituitary from far away


The cellular region to the left is the pars distalis. The fibrous region to the right is the pars nervosa.

You can also see a teeny bit of the intermedia in between the two.


• The intermediate lobe is ill-defined in humans. It consists of a thin zone of cells. Observe the cysts which represent the residual lumen of Rathke’s pouch.


pituitary gland: (1) chromophobe; (2) acidophil; (3) basophil


• How to distinguish acidophils and basophils: – look at the color of the red blood cells in the vessels (V).

– Then, match the color to cells in the pituitary. Those are the acidophils (A).

– Cells that are more "purple", or blue are the basophils (B).

– Cells that have hardly any color are the chromophobes


Anterior pit – sick of this yet?


• Somatotroph from the anterior pituitary. Notice the numerous, spherical secretory granules.

• The granules are full of GH


• Mammotroph from the anterior pituitary. The secretory granules are sparse and elliptical.

• Granules = prolactin


• The posterior lobe is smaller and lighter staining than the anterior lobe. It does not have the appearance of a glandular organ (i.e. FEWER nuclei). Note the masses of unmyelinated nerve fibers and pituicytes (round, dark nuclei).


Pars nervosa: This region consists of a mass of nerve fibers and endings from a fiber tract that extends down from the

hypothalamus. The hormones are stored in the nerve endings which can be quite large (called Herring bodies).


• pituicytes (purple nuclei throughout image) are neuroglia, which are supportive cells for the axons. ALL the nuclei are from pituicytes

PINEAL


• The most distinctive feature of this gland is the presence of "corpora arenacea" or "brain sand" in the aging pineal - it will help you identify the pineal. It is shown in the above photo as a large blue-purple mass in the tissue.


• Pinealocytes, with their pale, round nuclei can be seen along with a few glial cells. The smaller, dense nuclei belong to glial cells. Capillaries are also evident.

PARATHYROID


The parathyroid gland is distinguished by scattered clumps of adipose cells lying among the parenchymal cells. There are two types of parenchymal cells: chief cells and oxyphil cells.


• parathyroid glands synthesize parathyroid hormone. • Each gland is surrounded by a capsule from which

connective tissue septa extend inward and divide it into lobules.

• Two parenchymal cell types can be distinguished by H and E: the abundant chief cells (pale staining cytoplasm) and rarer LARGER oxyphil cells (acidophilic granules).


• THERE ARE NO DUCTS IN THE PARATHYROID GLAND. THIS IS HOW YOU TELL IT APART FROM THE PAROTID AND PANCREAS!!!!

• YOU’VE BEEN WARNED


• The chief cells have a low cytoplasm:nucleus ratio.

• Oxyphil cells are larger than chief cells and have slightly smaller and more intensely staining nuclei. These cells can be easily identified because a unit area contains few nuclei than a comparable unit area of chief cells.

THYROID


• The thyroid gland produces the thyroid hormones T3 and T4 or (thyroxin). The functional unit of the gland which synthesizes these hormones is the follicle. It consists of a layer of cuboidal epithelium (principal cells) enclosing the follicular cavity, which is usually filled with colloid


• A rich capillary network is present in the connective tissue separating the follicles. The principal thyroid cells (follicle cells) appear to form a “ring around the colloid.”


• EM of thyroid principal cell showing sparse microvilli on the apical surface that lies next to the stored colloid in the follicle.


• Parafollicular cells/C cells are found outside the colloid

ADRENAL GLANDS


• 3 regions of the cortex: – The outer region near the capsule has cells

arranged in clusters, like grapes. This is called the Zona Glomerulosa.

– The middle region has cells arranged in straight cords. It is called Zona Fasciculata The innermost region has cells arranged in a branching network. This is called the Zona reticularis.


To remember the order: remember GFR, which you loved to learn about in phys


• A higher magnification of the zona glomerulosa and the Zona fasciculata is shown in this photo. Note the many lipid droplets seen in the zona fasciculata cells.


In the medulla

And something that was on our final…..

In the liver, central veins drain into sublobular

veins…..


Central draining into sublobular

QUIZ TIME


WHAT CELL IS THE BLUE ARROW POINTING TO


pituicyte


• WHAT TISSUE IS THIS


• PARATHYROID – 2 types of cells, NO DUCTS


• A? B? C?

• .


• a = pale chromophobes

• b = blue basophil

• c = red acidophil

• The cells are separated by a fine reticular fibers (thin blue lines), where the blood capillaries lie.


TISSUE?


PINEAL (note brain sand)


• What cell is this?


• purple basophil

• Can be a thyrotroph, corticotroph, gonadotroph


COLLECTING DUCT

• You know bc you see thin limbs, so nothing else it can be


arrow


PARAFOLLICULAR or C-cell in thyroid

• If its not a follicular cell, it’s a parafollicular/c-cell

• In BETWEEN follicles


• Name that tissue


• Pars nervosa of pituitary• Note Herring bodies, collections of secretion in the

pars nervosa of the pituitary. They represent accumulations of neurosecretion within the axons of neurons whose cell bodies lie in the hypothalamus of the brain.


What is this?


THICK SKIN

• Lots of corneum


Tissue??


PARATHYROID

• The larger cells to the left are oxyphil cells whose function is unknown. They are found only in humans and increase with age. The intense eosinophilia in their cytoplasm reflects an abnormally high number of mitochondria in these cells.


Tissue?


THYROID

• This is the only endocrine gland that typically stores its hormonal secretion extracellularly before releasing it into the bloodstream.


What is this be specific


DUCT OF AN ECCRINE SWEAT GLAND

• Cuboidal

• Darker than the secretory end pieces


Ignore the arrow. What is this


GANGLION

• Fried eggs


• In general, where would be find this cell??


• adrenal cortex

• cytoplasm filled with smooth endoplasmic reticulum, typical of steroid - secreting cells. Parts of two mitochondria are also visible here.


Tissue?


DENSE REG CONNETIVE TISSUE

• Aka tendon

• Flat nuclei

• Wavy appearance


PARS RADIATA

• Found here are TAL and TDL and cortical collecting duct

• In pars convoluta are PCT, DCT, glomeruli, and connecting tubule


Tissue?


PANCREAS

• Look for the islets


Where are we?


In the gallbladder

• Do we see any goblets???????

• Do we see a muscularis mucosa???


QUESTIONS?

Endocrine Rachel Boggus [email protected]. 10/19/2015Template copyright 2005 Endocrine...

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Transcript of Endocrine Rachel Boggus [email protected]. 10/19/2015Template copyright 2005 Endocrine...