STRUCTURE OF THE RETINA 



723 



and disappear. The structure is quickly reduced to that of a simple 

 epithelial membrane known as the pars ciliaris retinae. 



At the pars ciliaris retinae, the retina is represented by a layer of columnar 



FIG. 451. Diagram of the Blood Vessels of the Human Retina. (Leber, after Jaeger.) 

 arts, vns, Superior nasal artery and vein; ats, vts, superior temporal artery and vein; ani, 

 uni, inferior nasal artery and vein; ati, vti, inferior temporal artery and vein; ant, vm, 

 macular artery and vein; ane, vme, median artery and vein. 



cells, derived from the fusion of the nuclear layers which are in contact with 

 the pigment layers of the retina and continued over the ciliary processes. 

 Pigment Layer. This layer, which was formerly considered part of the 



FIG. 452, Blood Vessels of the Macula Lutea. The part that is totally free from vessels is 



the fovea centralis. 



choroid, consists of cells which cover and entirely surround the outer limbs 

 of the rods and cones. 



Blood Vessels of the Eyeball. The eye is very richly supplied with blood 

 vessels. In addition to the conjunctival vessels, which are derived from the 



