Sence organs: Eye IV

Sence organs: Eye IVHistology 2016-2017
Department of Anatomy &Histology: Dr.Rajaa Ali
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Sence organs: Eye IV
1. Cornea .
2. Aqueous humour
It is present in anterior and posterior chambers (described with sclerocorneal junction).
3. Vitreous body
It is the transparent gel present behind the lens.
It is made of water (99%), hyaluronic acid and collagen fi brils.
4. Lens
Lens is a transparent, fl exible biconvex disc, that alters its refractive power by changing its curvature.
Its posterior surface is less curved than the anterior surface.
It lies behind the iris and its most convex anterior surface is in contact with the pupillary margin of the iris.
It is held in position by the suspensory ligament of lens which attaches the equator of the lens (circumferential border) with the ciliary processes.
Lens comprises three components, namely, capsule, anterior subcapsular epithelium and lens substance (Fig.).
Capsule—is a homogeneous elastic basement membrane that envelops the entire lens. It is made of type IV collagen and proteoglycans.
Anterior subcapsular epithelium—is a simple cuboidal epithelium covering only the anterior surface of lens beneath the capsule. Towards the equator of lens, the cuboidal cells become columnar and become lens fi bres.
Lens substance—is formed by lens fi bres that are laid concentrically around the original central core by differentiation and elongation of anterior lens epithelial cells