THORAX AND ABDOMEN OF THE HORSE 



75 



some mammals septules of fibrous tissue run into the testis from this 

 tunic and converge towards the mediastinum'^ testis, an elongated mass 

 of fibrous tissue placed near the dorsal border. The presence of septules 

 causes the division of the testicular parenchyma into lobules, each 

 lobule presenting a granular appearance on section due to the circum- 

 stance that it is composed of richly convoluted seminiferous tubules. 

 A relatively thin but loose and highly vascular tissue, sometimes 

 called the tunica vasculosa testis, lies within the tunica albuginea and 

 extends over the septules, and serves to distribute blood vessels to the 

 lobules. 



In the horse, neither septules nor mediastinum are very distinct. 



/I B 



Serous layer of tunica vaginalis. 

 Visceral serous membrane. 



Skin. 1 I 

 Tunica dartos. 

 Tunica dartos 

 Skin. I 



Pampiniform plexus (venous) 

 M. cremaster externus. 



Testis. 



A. spermatica - 

 interna. 



Serous layer of 

 tunica vaginalis. 



Ductus deferens. 

 Fibrous layer of tunica vaginalis. / / 



Fibrous layer of tunica vaginalis. ' 

 M. cremaster externus. 



Sinus epididymidis. 



Septum 

 scroti. 



Ductus deferens. 



Epididymis. 



Fig. 33. — Horizontal sections through the scrotum (semi-diagraniniatic), 

 ^=above the testis. fl = on a level with the testis. 



The prepuce (Pra^putium). — The prepuce -is a tubular sheath of 

 integument enclosing the free portion of the penis, and in the retracted 

 state of this organ, circumscribing a cavity that communicates with the 

 exterior by a large preputial orijice (ostium praeputiale) situated close 

 beliind the umbilicus. 



The prepuce consists of two layers : a parietal and a visceral. The 

 parietal layer presents a superficial sheet composed of skin continuous 



' Mediastinum [L.], a median partition or sei)tum ; mediastinus [L.], being in 

 the middle, a common servant. 



- Prcepniium [L.], the foreskin ; the root is pu, to generate, to produce. 



