358 



HISTOLOGY. 



conical outer segments are shorter than those of the rods. The inner 

 segments are thick and somewhat dilated so that the entire cone is flask- 

 shaped. Moreover, the inner segment contains a vertically striated "fiber 

 apparatus." The nuclei of the cone cells are situated just beneath the 

 limiting membrane; below the nuclei the protoplasm forms a fiber ending 

 in an expanded pyramidal base. 



Beneath the outer nuclear layer there is a zone of fibers called the 

 outer reticular layer [outer molecular layer]. It contains but few nuclei. 

 The basal fibers of the visual cells are sometimes described as forming its 

 outer part; more specifically they are called Henle's fiber layer. The 



Chorioid. 



Pigmented -1 

 epithelium. 



Layer of rods and J 

 cones. 



Membrana limitans 

 externa. 



Outer nuclear f 

 layer. 



Henle's fiber layer. _* 





Inner reticular 

 layer. 



Inner nuclear j 

 layre. 



f ., Vessels of the 

 choriocapil- 

 laris. 



*; "Lamina basalis. 



Rods ' Outer. 

 Cones \ segment. 



' Cones i 



Rods 



Inner 



' Inner reticular j 

 layer. 



Ganglion cell layer. 



H 

 Nerve fiber layer. - 





Base of a cone fiber. 



Nucleus of a radial 

 fiber. 



Nucleus of an 

 amakrine cell. 



Pyramidal base of 

 a radial fiber. 



Membrana limitans 

 interna. 



Blood vessels. 

 FIG. 411. VERTICAL SECTION OF A HUMAN* RETINA. 



X 36. 



remaining portion is a dense network of the branching processes from 

 underlying nerve cells. Occasionally a cell body is displaced outward 

 from the deeper layer and comes within the reticular layer. One of such 

 "subepithelial ganglion cells" is seen in Fig. 412, x. The nervous ele- 

 ments are supported by a fibrillar network derived from non-nervous 

 ectodermal cells, corresponding with neuroglia. Some of the supporting 

 cells found in the reticular layer are concentrically arranged (Fig. 412, oo). 

 The inner nuclear layer, which underlies the outer reticular layer, 

 contains the cell bodies of both nerve and sustentacular cells. The nuclei 

 of the latter belong chiefly with radial fibers [Miiller's fibers]; these extend 

 from the inner surface of the retina to the membrana limitans externa. 



