SPERM ATOGENESIS INSEMINATION 



161 



In embryonic development the tubules arise from the primitive 

 germinal epithelium. According to Allen l the interstitial cells are 

 derived from connective tissue. 



The straight tubules, and the tubules of the rete, are lined by a 



FIG. 47. Section through testis of monkey. 



a, Seminiferous tubules ; ft, interstitial tissue ; e, rete testis ; </, vasa 

 efferentia ; e, vas deferens ; /", tunica albuginea. 



single layer of cubical or flattened epithelium without a basement- 

 membrane. The seminiferous tubules, on the other hand, contain 

 several layers of epithelial cells supported by a thick basement- 



1 Allen, "The Embryonic Development of the Ovary and Testis," A ///</-. 

 Jour, of Anat., vol. iii., 1904. As already mentioned, Allen regards the inter- 

 stitial cells of the ovary as being developed from connective tissue, thus differing 

 from Miss Lane-Claypon. 



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