276 



HISTOLOGY. 



the interstitial cells at first increase; later they are destroyed. At the same 

 time the basement membrane becomes thickened and hyaline, fat drop- 

 lets accumulate, and the sexual cells disappear, leaving the sustentacular 

 cells. 



The vessels and nerves of the testis enter the mediastinum and tunica 

 albuginea, having followed the ductus deferens in the spermatic cord. 

 The convoluted tubules are surrounded by capillary networks derived 

 from branches of an artery to a Wolffian glomerulus, and are drained by 

 capillary branches of the Wolffian sinusoids. The main stems of these 

 vessels are called internal spermatic. Lymphatic vessels are numerous in 

 the tunica albuginea and they extend among the tubules. Nerves from 

 the spermatic plexus accompany the blood vessels; the presence of intra- 

 epithelial endings has not been established with certainty. 



EPIDIDYMIS. 



The efferent ducts which pass from the rete to the duct of the epididy- 

 mis are lined with an epithelium in which groups of columnar cells alter- 



Tangential section 



of a ductulus 



efferens. 



<.-i-v-> m . gf'&mmL 



Blood vessel. Epithelium Circular muscles 



of the ductus epididymidis. 



Transverse section of a 

 ductulus efferens. 



FIG. 313. FROM A SECTION OF THE HEAD OP A HUMAN EPIDIDYMIS, SHOWING SECTIONS OF THE DUCTUS 

 EPIDIDYMIDIS IN THE CENTER AND OF DUCTULI EFFERENTES ON THE SIDES. X 50. 



nate with those which are cuboidal (Figs. 313 and 314). Thus the inner 

 surface of the epithelium has depressions suggesting glands, but the basal 

 surface is free from outpocketings. The epithelium is generally simple, 

 although .in the tall parts it may appear 2 or 3 layered. The cells con- 



