352 



NORMAL HISTOLOGY. 



fibres of Miiller, which extend through the entire thickness of 

 the retina. The expanded inner ends of the supporting fibres are 

 so closely applied that they produce a seemingly continuous mem- 

 brane, the so-called membrana limitans interna. The radial 

 fibres rapidly diminish in diameter beyond their bases, and are con- 

 tinued as nai row irregular stalks giving off lateral branches in pro- 

 fusion to the reticular layers ; within the inner nuclear layer each 

 fibre presents an irregular nucleated enlargement, and gives off 

 lateral processes for the support of the nervous elements of the inner 

 nuclear layer, as well as to each of the succeeding layers. At the 



FIG. 376. 



Diagram illustrating the relation of the retinal elements. A, layer of rods and cones; B, limitans 

 externa ; C, outer nuclear layer ; E, outer reticular layer (between the two (D) Henle's fibre-layer) ; 

 F, inner nuclear layer ; G, inner reticular layer ; ff, layer of ganglion-cells ; /, fibre-layer ; K, limitans 

 interna. a, supporting fibres of Miiller; b, c, rod- and cone- visual cells; d, bipolars belonging to 

 rod-cells ; ei, bipolars belonging to cone-cells ; k-in, horizontal nerve-cells ; n, centrifugal nerve-fibres ; 

 o-t, ganglion-cells connected with optic fibres ; a-e, spongioblasts or amacrines arranged in layers ; 

 , $, diffuse amacrines ; rj, nervous amacrine. (Kallius after Ramon y Cajal.) 



inner border of the rods and the cones the expanded ends of the neu- 

 roglia-fibres form the external limiting membrane, delicate pro- 

 cesses extending from the latter between the bases of the rods and the 

 cones, which they surround and embrace as the " fibre-crates." 

 In addition to the long radial fibres, richly-branched neuroglia- 

 cells occur within the outer reticular layer to the fibre-complex of 

 which they contribute. 



Within the meshes of the framework just described the ner- 

 vous elements of the retina are distributed in a manner charac- 

 teristic for each layer : a brief consideration of these is therefore 

 necessary. 



