276 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



testicle and is derived from the peritoneum during 

 the descent of the organ. It is therefore a serous 

 coat that has the same histology as the peritoneum, 

 and may be divided into two parts, one the visceral 

 portion that invests the surface of the organ, and the 

 other the parietal portion that is reflected over the 

 surface of the infundibuliform fascia. The interval 

 between these portions constitutes the cavity of the 

 tunica vaginalis, and it is in this space that hydro- 



Tunica vaginalis, visceral portion. 



Tunica vagi- 

 nalis, parie- 

 tal portion. 



Tunica albuginea. 



Epididymis. 



Vas deferens. 



Lobule. 

 Fig. 207. Cross section of human testicle. 



cele fluid collects. (7) The tunica albuginea comes 

 next and is a firm fibrous covering. This tunic 

 sends fibrous cords or trabeculae into the testis, 

 which divide the organ into lobules. It is par- 

 ticularly dense along the posterior margin of the 

 organ where it also invests the vas deferens, forming 

 at this margin a mediastinum called the corpus of 

 Highmore. (8) The tunica vasculosa is a delicate 

 vascular layer that covers the inner surface of the 



