Histology Of The Eye

Endre Dobó

> fibrous coat > cornea > sclera blind part of retina [1+1 layers] ora serrata [boundary; 9 layers reduced to 1 here] optic part of retina [1+9 layers]

> vascular coat / uvea > choroid > ciliary body > iris > nervous coat / retinal layer > as to the development > neural layer > pigment epithelium > as to the structure > blind part of retina > (ora serrata) > optic part of retina > retina proper

main layers: > fibrous coat / corneoscleral layer (tunica fibrosa) > cornea > (corneo-scleral junction) > sclera > vascular coat / uveal layer (tunica vasculosa bulbi / uvea) > choroid > ciliary body (corpus ciliare) > iris > sensory coat / nervous layer (tunica nervosa bulbi) > as to the development of the eyeball > neural layer (str. cerebrale) > pigment layer (str. pigmentosum / str. pigmenti retinae) > as to the anatomical structure > blind part (pars coeca retinae) > (ora serrata) > optic part (pars optica retinae) > retina proper

retina

choroid

sclera

extra-ocular muscle

layer of the afferent fibers (9.) ganglion cell layer (8.) inner nuclear layer (6.) outer nuclear layer (4.) rod and cone processes (2.) pigment cells (1.) choroid sclera

> anterior one-sixth of the this main layer > transparent > its junction with the conjunctiva: limbus > sensory innervation by long ciliary nerves [n. V/1] > lacks vasculature (!) > layers > corneal epithelium (epithelium corneae / epithelium anterius corneae) > stratified squamous epithelium > underneath, there are no connective tissue papillae > free nerve endings from ophthalmic nerve [n. V/1.] > Bowman's membrane (lamina limitans anterior / membrana limitans anterior) > acidophil, cell-free membrane > if injured, it loses its transparency > substantia propria corneae > stroma > keratocytes > highly regular form of dense collagenous tissue > Descemet's membrane (lamina limitans posterior) > acidophil basement membrane > corneal endothelium / corneal mesothelium (endothelium camerae anterioris) > simple squamous epithelium

> posterior five-sixths of the this main layer > opaque > contains few blood vessels > provides insertion for the extra-ocular muscles > layers > lamina fusca sclerae > thin layer with occasional melanocytes > may be considered articial layer on the inner surface of sclera > scleral stroma > densely collagenous, hypocellular tissue with elastic fibers > episcleral layer > connected with Tenon's capsule by fine delicate collagenous fibers > important anatomical part > lamina cribrosa > perforated layer of the slcera for the passage of optic nerve fibers

> from external view > conjunctival ring > beginning of the conjunctiva of the eyeball > scleral sulcus > in the middle" > limbus corneae (corneoscleral junction) > from internal view > Descemet s membrane terminates, and trabecular meshwork begins > iridocorneal angle (angulus iridocornealis) > trabecular meshwork (spongiosa sclerae) > drainage of aqueous humor (humor aquosus) > parts > trabecules / pectinate ligaments > spaces of Fontana (spatia anguli iridocornealis) > there is NO endothelial lining > is not continuous with the canal of Schlemm > canal of Schlemm (sinus venosus sclerae / canalis Schlemmi) > single circular vessel, lined by endothelium > minute channels (venae aquosae) through the sclera lead to the episcleral venous system

corneal epithelium conjunctival ring substantia propria corneae Descemet s membrane iridocorneal angle trabecular meshwork canal of Schlemm ciliary epithelium

> layers > suprachoroidal lamina (lamina suprachoroidea) > contains only a few vessels and pigment > houses the ciliary nerves, posterior ciliary arteries and the vorticose veins > perichoroidal space (spatium perichoroideale) > spatial system, part of which forms lymph pathways > vascular lamina (lamina vasculosa / lamina vascularis) > precapillary arterioles and postcapillary venules > choriocapillary layer (lamina choroidocapillaris / lamina choriocapillaris) > network of fenestrated capillaries > Bruch's membrane (lamina vitrea / lamina basalis) > double layer of basement membranes > blood-retina barrier

> anatomical structure > orbiculus ciliaris (pars plana) > ciliary m. (m. ciliaris) > fibrae meridionales > fibrae radiales > fibrae circulares > corona ciliaris (pars plicata) > ciliary folds (plicae ciliares) > ciliary processes (processus ciliares) > aqueous humor (humor aquosus) is secreted here > zonula ciliaris [lencse függeszt készüléke] > suspensory ligament of Zinn (fibrae zonulares) > attached to the coronal equator of the lens > histological structure > stroma corporis ciliaris > loose connective tissue, with capillary network and ciliary muscles > epithelium (pars ciliaris retinae) > outer layer is pigmented > inner layer is NOT pigmented

stroma corporis ciliaris epithelium ciliare outer pigmented layer inner NOT pigmented layer

ciliary processes

> anatomical structure > pupillary margin (margo pupillaris) > lesser arterial circle of iris (circulus arteriosus iridis minor) > ciliary margin (margo ciliaris) > greater arterial circle of iris (circulus arteriosus iridis major) > pectinate ligaments (ligamenta pectinata) > among them: spaces of Fontana (spatia anguli iridocornealis) > histological structure > anterior surface (endothelium camerae anterioris) > discontinuous epithelium, intermingled with melanocytes and fibrocytes > stroma iridis > constrictor m. of the pupil (m. sphincter pupillae) > innervated by parasympathetic fibers from the oculomotor n. > pigmented cells (melanocytes) > dilator pupillae m. (m. dilatator pupillae) > smooth muscle cells (neuroectodermal by origin) or > pigmented (!) myoepithelial cells > innervated by sympathetic fibers from the carotid plexus) > (membrana limitans iridis) > membrana basalis > pigmented epithelium (str. pigmenti iridis / str. pigmentosum / pars iridica retinae) > bilayered epithelium

endothelium camerae anterioris

stroma iridis

melanocytes

sphincter pupillae m.

dilatator pupillae m.

pigmented epithelium

> parts - as to the development > neural retina (str. nervosum / str. cerebrale retinae) > 9 inner histological layers > pigment epithelium (str. pigmentosum retinae) > 1 layer simple epithelium, which is pigmented > parts - as to the anatomy > light-INsensitive part (pars coeca retinae) > contains NO photoreceptors > pars ciliaris retinae > pars iridica retinae > (ora serrata - ora serrata) > here reduce the 10 layers into 2 cell layer of pars coeca > light-sensitive part (pars optica retinae) > contains photoreceptors (rodes and cones)

> (1) > (2) > (3) > (4) > (5)

> (6)

> (7) > (8) > (9)

> (10)

> str. pigmentosum / str. pigmenti retinae (pigment epithelium) > pigmented epithelium > str. neuroepitheliale / str. bacilli et coni (rod and cone processes) > processes of light-sensitive cells: rods (bacilli) and cones (coni) > str. limitans externum / membrana limitans externa (outer limiting membrane) > formed by Müller cells (glial cells) > str. granulosum externum / str. nucleare externum (outer nuclear layer) > somata of the photoreceptor cells > str. plexiforme externum (outer plexiform layer) > between the receptor cells and bipolar cells > between the horizontal cells and receptor cells > str. granulosum internum / str. nucleare internum (inner nuclear layer) > neurons: bipolar and horizontal neurons, amacrine cells > cell bodies of Müller cells > str. plexiforme internum (inner plexiform layer) > between the bipolar neurons and ganglion cells > str. ganglionare (ganglion cell layer) > ganglion cells > str. neurofibrarum (layer of the afferent fibers) > unmyelinated optic nerve fibers > here branch the retinal central blood vessels > str. limitans internum / mebrana limitans internum (inner limiting membrane) > formed by Müller glial cells; demarcates the innermost aspect of the retina from the vitreous body

> principal refracting media of the eye > cornea > lens of eye (lens crystalina) > non-refracting optical media of the eye > aqueous humor (humor aquosus) > vitreous body (corpus vitreum)

> ciliary process of ciliary body > posterior chamber > anterior chamber > spaces of Fontana of the trabecular meshwork (between the pectinate ligamants) > canal of Schlemm (sinus venosus sclerae) > venae aquosae (small-caliber blood vessels) > episcleral veins

> bulbar conjunctiva (conjunctiva bulbaris / conjunctiva bulbi) > continuous with the cornea > non-keratinized stratified squamous epithelium > connective tissue papillae > lamina propria > (conjunctival fornix [fornix conjunctivae [reflection]) > stratified columnar epithelium > palpebral conjunctiva (conjunctiva palpebralis / conjunctiva palpebrae) > stratified columnar epithelium > close to the fornix > goblet cells occur in the outermost layer (!!!) > non-keratinized stratified squamous epithelium > close to the anterior palpebral edge > small lacrimal glands may appear in the entire conjunctiva

> elastic biconvex structure > structure > lens capsule (capsula lentis) > 10-20-mikrometer thick membrana basalis > anterior surface > subcapsular epithelium (epithelium anterius) > single cuboidal epithelium > (lens equator) > posterior surface > lens fibers (fibrae lentis) > epithelial cells > losing their nuclei: anucleate fibers > stretch between the anterior and posterior poles of the lens > contain crystalline protein

the eye is partioned by the lens, suspenssory ligament and ciliary body into: > smaller anterior compartment > filled with aqueous humor > watery fluid, hypotonic with respect to plasma > secreted by the ciliary processes of ciliary body > source of nutrients for the non-vascular lens and cornea > parts > anterior chamber (camera bulbi anterior) > bordered by cornea, iris and lens > posterior chamber (camera bulbi posterior) > bordered by lens, suspensory ligament and ciliary body > large posterior compartment > contains vitreous body > gelatinous mass > consisting of vitreous humor > 99% is water & hyaluronic acid > hyaloid canal / Cloquet s canal (canalis hyaloideus) > hyaloid artery during embryological development > vitreous membrane / hyaloid membrane > condensation of fibers on the surface of the vitreous body