ANATOMY EVALUATION (LAB) 11Source:Esteban and Gonzales’ Textbook of Histology

EYE HISTOLOGY3 histologic layers:

1. TUNICA FIBROSA (fibrous layer): CORNEA, SCLERA2. TUNICA VASCULOSA (uvea): CHOROIDS, CILIARY BODY, IRIS3. TUNICA INTERNA (retina): RETINA ( anterior, posterior)

ANTERIOR EYE

Bowman’s membrane8-12µmAcellular and amorphous

Descemet’s membraneHomogenous layer thinner than bowman’s membraneBasement membrane formed by basal lamina

EndotheliumSimple cuboidal epitheliumForms part of DM

Epithelium NKSS, 5-6 layersIn between are numerous free sensory nerve endings that’s why cornea is very sensitive

STROMA

CORNEA- anterior 1/6, transparentThicker than the scleraThe central region is slightly thinner than its peripheral regionRichly supplied by sensory nerves but avascular

SCLERA

IRIS

CANAL OF SCHLEMM

Sclera- posterior 5/6, opaqueTough dense irregular connective tissueEmbedded near the limbus is the canal of Schlemm

Canal of SchlemmCircumferential system of endothelium lined , irregular interconnecting canalServes as drainage channel for aqueous humor from the anterior chamber

TUNICA FIBROSA has 2 regions: sclera (posterior 5/6) and cornea (anterior 1/6) The sclera and cornea are continous with each other at the CORNEO-SCLERAL

JUNCTION (LIMBUS) denoted by shallow groove internall and externally

LIMBUS

IRIS

CORNEA

SCLERA

Bulbar conjunctiva overlies the sclera Thin translucent mucous membrane that

covers the ant. portion of the sclera

UVEA (TUNICA Vasculosa) 3 PARTS: CHOROIDS, CILIARY BODY, and IRIS

CHOROIDS (picture from demo slide) vascular pigmented layer that forms the middle histologic layer of the posterior 2/3 of the eyeball Attached to sclera by a thin layer of loose CT ( SUPRACHOROIDAL LAMINA)

CILIARY BODY Forms a ring of tissue on the inner surface of the anterior portion of the sclera

IRIS

NOTE: @ pointer pigmented epithelium detached from retina

The ciliary body has 2 regions:Epithelial portion- adjacent to vitreous cavity and equator of the lens; it is covered posteriorly by CILIARY RETINA

(part of the anterior non photosensitive portion of the retina)SUBDIVIDED INTO: PARS PLANA &PARS PLICATA- with numerous fingerlike projections called CILIARY PROCESSES

Uveal portion-adjacent to sclera and is mainly made up of smooth muscle fibers that comprise the CILIARY MUSCLES

Retina

Choroid

Sclera

CILIARY BODY

@ pointer: CILIARY PROCESSES (where aqueous humor is derived)

SCLERA

IRIS

Ciliary muscles

Highly pigmented and vascular diaphragm Anterior to the lens and covers the lens incompletely leaving a round central opening- PUPIL It regulates the amount of light that enters the eye by adjusting the size of the pupil Substance is primarily loose CT richly supplied by capillaries and which are embedded in numerous

melanocytes, fibroblast and smooth muscles Melanocytes accounts for the color of the eye: few-blue eyes, numerous- brown eyes

CHAMBER The cavity of the eye is divided into 3 compartments: 1. anterior chamber (bounded by cornea anteriorly and iris and lens posteriorly),2. posterior chamber ( bounded by iris anteriorly and ciliary processes and zonule fibers laterally and

posteriorly)3. vitreous chamber (large spherical compartment behind the lens, zonule fibers and ciliary proceses) Aqueous humor fills the anterior and posterior chamber while vitreous humor fills the vitreous chamber

LENS Biconvex elastic structure; more convex at posterior than the anterior surface

IRIDIAL RETINACovers the posterior surface of the iris

IRIS

LENS

Constrictor papillae muscle- constrict the pupil when stimulated by parasympathetic impulses

ANTERIOR CHAMBER

SCLERA

CORNEA

LIMBUS

IRIS

IRIS

LENS

POSTERIOR CHAMBER

Highly cellular and amorphous Enveloped by thick lens capsule Deep to the lens capsule, the anterior surface is covered by simple cuboidal epithelium- SUBCAPULAR

EPITHELIUM LENS FIBERS- composed the substance of the lens, 2000-3000 specialized cells that have lost the nuclei and

other organelles

LACRIMAL GLAND A serous gland located in the antero-superior temporal portion of the orbital cavity

LENS FIBERS

LENS CAPSULE

SUBCAPSULAR EPITHELIUM

Consist of several separate lobes that empty into the superior conjunctival fornix via 6-12 excretory ducts A tubuloalveolar gland similar to parotid gland Secretory portion consist of serous secreting cells

EYEBALL- LAYERS OF THE RETINA

Interlobular duct found in the connective tissuebetween lobules and lobes; interlobular ducts unite forming LOBAR ducts

NOTE: Encapsulated by dense irregular CTThe elements from the capsule invade the substance of the gland to divide into lobes and lobules filled purely with serous acini and ducts

NOTE that associated with the acinar cells are myoepithelial cells ( flat,contractile cells that are lodge between the epithelial cells and basal lamina)

RETINA is the innermost histologic layer of the eyeball; has 2 regions: anterior retina and posterior retina (retina proper)

Cells of the posterior retina are arranged and well organized, there are 10 histologically distinct layers (external to internal)

DEMO SLIDES

12

5

3

4

7

8

Choroid

6

910

1 2 3 5

CHOROID

86 74 9 10

LAYERS1 - Pigment layer2- Layer of rods and cones3- Outer limiting membrane4- Outer nuclear layer5- Outer plexiform layer6- Inner nuclear layer7- Inner plexiform layer8- Ganglion cell layer9- Nerve fiber layer10- Inner limiting memebrane

LAYERS OF CHOROID AND RETINA: PIGMENT EPITHELIUM WHICH HAS DETACH FROM RETINA

SINGLE ROW OF CUBOIDAL CELLS @ POINTER COMPRISE THE PIGMENT EPITHELIUM W/C DETACH FROM THE REST OF THE RETINA (A)

SINGLE ROW OF DARK CELLS @ POINTER COMPRISE THE PIGMENT EPITHELIUM W/C DETACH FROM THE REST OF THE RETINA (B)

Eyelids (palpebrae) Upper and lower- thin folds of tissues that protect the anterior portion of the eyeball

SCLERA

CHOROID

RETINA

PIGMENT EPITHELIUM

A B

The external surface is lined is covered by skin while internal surface is lined by palpebral conjunctiva

The skin contains some hairs except the free edge of the eyelid where 2-3 rows of course long hairs (eyelashes) project anteriorly

types of glandsMeibomian glands (mg)numbering 20-25 per eyelid,atypical sebaceous glands because they are not associated with hair follicles and they have long ducts into numerous acini drainlocated within the tarsal plate, and ducts open @ free edge of the eyelidMollModified apocrine sweat glandLocated @ the dermis and ducts empty into the follicles the eyelashesZeis Sebaceous gland Smaller than Meibomian glandLocated @ the dermis and ducts empty into the follicles the eyelashes

Tarsal Plate A fibroelastic plate that consist the core of the eyelidAnterior to this are skeletal muscle fibers that comprise the orbicularis oculi muscle and at the upper eyelid-levator palpebrae

Tarsal gland (meibomian)

Eyelash (hair Follicle)

Epidermis

Dermis (connective tissue + adipose tissue)Glands of Moll

Orbicularis oculi

Palbebral conjunctiva

Tarsal gland (meibomian)

Bulbar conjunctiva