26-2 THE ESSENTIALS OF HISTOLOGY. 



angles in the alternate laminae. Between the laminae lie flattened con- 

 nective-tissue corpuscles, which are branched and united by their 

 processes into a continuous network ; there is of course a corresponding 

 network of cell-spaces (fig. 290, A, B). In vertical sections the cells 

 appear narrow and spindle-shaped (fig. 289, c). In the superficial 

 laminae there are a few bundles of fibres which run obliquely towards 

 the surface (a). 



4. A homogeneous elastic layer (membrane of Descemet, fig. 289, 4). 

 This completely covers the back of the cornea, but at the angle which 

 the cornea forms with the iris it breaks up into separate fibres, which 

 are continued into the iris as the ligamentum pectinatutn, or pillars of 

 the iris. 



FIG. 291. SECTION OF CHOROID. (Cadiat.) 



a, membrane of Bvuch : the chorio-capillaris is just above it; b, vascular layer ; c, vessels 

 with blood-corpuscles ; d, lamina suprachoroidea. 



5. A layer of pavement-epithelium (endothelium of Descemet's mem- 

 brane) covering the posterior surface of the elastic lamina, and lining 

 the front of the anterior chamber of the eye (fig. 289, 5). At the sides 

 it is continued over the ligamentum pectinatum into a similar endothe- 

 lium, covering the anterior surface of the iris (fig. 294). The cells of 

 the epithelium of Descemet's membrane are separated from one another 

 by intercellular spaces, bridged across by bundles of fibrils which pass 

 through the cells. 



The nerves of the cornea pass in from the periphery, losing their 

 medullary sheath as they enter the corneal substance. They form a 

 primary plexus in the substantia propria, a secondary or sub-epithelial 

 plexus immediately under the epithelium which covers the anterior- 

 surface, and a terminal plexus of fine fibrils which pass from the sub- 

 epithelial plexus in pencil-like tufts and become lost between the epi- 

 thelium-cells (see figs. 125, 126, Lesson XXL). There are no blood- 

 vessels or lymphatics in the cornea, although they come close up to its 

 margin. 



The choroid or vascular coat of the eye is of a black colour in many 



