VISUAL ORGAN. 



343 



form of a reticular network, the so-called lamina cribrosa. 

 The eye muscles attach themselves to the sclera in such a way 

 that their tendons pass over into the fibril bundles of the 

 sclera. The outer surface of the sclera borders on the con- 

 junctiva sclerse, with which it is bound by the loose subcon- 

 junctival connective tissue. 



(2) Tunica Media. 



In the chorioidea we distinguish several layers (Fig. 261) : 

 1. The lamina vasculosa is the outermost layer, and is adja- 

 cent to the lamina suprachorioidea. It contains large blood- 

 vessels, the branches of the venae ciliares posticse, and the 

 arterise ciliares posticse brevis. The ground substance consists 



FIG. 26L 



Pigment layer 

 of retina 



Lamina *"-| 



basalix -4! 



Lamina 

 chorio- 



capillaris 



Lamina 



vasculosn 



Lamina supra- 



chorioidea 



Part of the 



Vertical section through the chorioidea and a part of the sclera of an ape. X 440. 



of connective tissue with fine elastic fibre networks. In it there 

 are veins surrounded by lymph spaces. Numerous pigment 

 cells are present, and running along the arteries are bundles 

 of smooth muscle cells and flat branched cells. 



2. The lamina choriocapillaris lies internal to the lamina 

 vasculosa, It consists of a small amount of ground substance 

 containing a capillary plexus, which is more dense in the region 

 of the macula hi tea. No pigment is present. 



3. The lamina basalts is a highly refractive, delicate mem- 



