THE TESTIS. 



229 



In contrast to the dense fibre-elastic tissue of the framework of the testis, 

 the interstitial connective tissue between the seminiferous tubules is 



Blood-vessel 



Seminiferous tubule, 

 cut obliquely 



Tunica albuginea 



Seminiferous tubule, 

 cut transversely 



Group of interstitial cells 



Tunica vaginalis 



FIG. 279. Transverse section of testis, showing dense fibrous capsule and adjacent seminiferous 



tubules. X 30. 



loose, consisting of delicate bundles of white fibrous tissue with few elastic 

 fibres. In addition to plate-like connective tissue cells, leucocytes and eosin- 

 ophiles that occur in varying 

 numbers, the intertubular or in- 

 terstitial stroma contains groups 

 or cord-like masses of peculiar 

 rounded polygonal elements, the 

 interstitial cells. These cells 

 (15-20 IJL in diameter) possess 

 relatively small eccentric nuclei 

 and finely granular cytoplasm 

 that usually lodges numerous 

 fatty droplets, or lipoid gran- 

 ules, and crystalloids (mito- 

 chondria) in the form of minute 

 needles or rods. The signifi- 

 cance of these cells is uncertain, 

 but they are probably modified 

 connective tissue elements con- 

 cerned in the production of an 

 internal secretion related to sex. 

 The Seminiferous Tu- 

 bules. The secreting tubules 

 consist of a tunica propria, or 

 basement membrane, which en- 

 closes several layers of epithe- 

 lial cells. These vary not only before and after the attainment of sexual 

 maturity, but subsequent to the latter with functional activity or rest. 



Dilated duct 



Connecting 

 canal 



Epithelium 



FIG. 280. Section of mediastinum, showing irregular 

 channels of rete testis. X 60. 



