Author/Editor		Štiblar-Martinčič, Draga
Title		Razvoj očesa
Translated title		Development of the eye
Type		članek
Source		Med Razgl
Vol. and No.		Letnik 43, št. 3
Publication year		2004
Volume		str. 231-43
Language		slo
Abstract		The eye and, the sensory organ for vision, develops from the sensory placodes in the ectodermal germ layer like the other sense organs, in response to induction from the central nervous system. A single eye field separates into two optic primordia after sonic hedgehog stimulus expressed in the prechordal plate. Eye development is first evident at the beginning of the fourth week. The basic structures for eye development are the neuroeaodermal optic vesicle, which is a lateral evagination from the wall of the diencephalon, neural crest ectomesenchyme and the overlying surface eaoderm. Further development is coordinated by successive signals and interacting intluences of the above-mentioned tissues. The optic vesicle contacts the surface ectodexm and triggers a response that leads to thickening of the eaoderm, the so-called lens placode, which later develops into a mature lens. While the lens placode internalizes to form the lens vesicle, the distal optic vesicle invaginates to form the optic cup. The inner layer of the optic cup develops into the neuroretina, while the outer layer forms the rerinal pigmented epithelium. The proximal region of the optic vesicle is the optic stalk that connects the optic vesicle with the rostral part of the diencephalon. Prom the optic stalk, the optic nerve develops. Thmugh the optic fissure, the hyaloid artery enters the eye and its proximal part is left as the central retinal artery. Successive signals between the optic vesicle, surrounding mesenchyme in the ectoderm around the lens placode induce the development of auxiliary eye structures. The genes which are crucial for eye development are Pax2 and Pax6.
Summary		Specialna čutila, kamor prištevamo tudi čutilo vida oko, se razvijejo iz čutnih plakod v ektodermalnem kličnem listu kot odgovor na spodbudo iz osrednjega živčnega sistema. Prvotno se eno očesno polje na pobudo signalov "sonic hedgehog-a" iz prehordalne plošče loči v dve piimarni očesi. Prvi zametki očesa se pojavijo na začetku četrtega tedna razvoja. Primarne strukture, iz katerih se razvije oko, so nevroektodermalni očesni mehurček kot stransko ugrezanje stene diencefalona, ektomezenhim nevralnega grebena in površinski ektoderm. Nadaljnji razvoj očesa usklajujejo zaporedni signali in medsebojni vpliv omenjenih tkiv. Očesni mehurček sproži v stiku s površinskim ektodermom zadebelitev ektoderma v lečno plakodo, iz katere se razvije leča. Medtem ko se lečna plakoda preoblikuje v lečni mehurček, se distalni del optičnega mehurčka ugrezne v obliko očesne čaše. Notranja plast očesne čaše se razvije v živčni del mrežnice, zunanja plast tvori pigmentni epitelij. Proksimalni del očesnega mehurčka je očesni pecelj, ki povezuje očesni mehurček z rostralnim delom diencefalona. Iz očesnega pedja nastane vidni živec. Skozi očesno špranjo pride v oko hialoidna arterija, katere proksimalni del ostane kot centralna arterija mrežnice. Medsebojni signali med očesnim mehurčkom, okolnim mezenhimom in ektodermom v predelu lečne plakode spodbudijo razvoj pomožnih struktur očesa. Gena, ki sta ključnega pomena za razvoj očesa, sta Pax2 in Pax6.
Descriptors		EYE CORNEA CONJUNCTIVA RETINA LENS, CRYSTALLINE UVEA IRIS OPTIC NERVE EYELIDS LACRIMAL APPARATUS EYE ABNORMALITIES