THE REPRODUCTIVE ORGANS. 



753 



propria, which appears as a hyaline elastic membrane, but which is 

 really made up of several incomplete layers of flattened cells, contain- 

 ing oval flattened nuclei at regula,r intervals. Inside this membrana 

 propria are several layers of epithelial cells, the seminal cells (fig. 449). 

 These consist of two or more layers, the outermost being situated next 

 the membrana propria. These cells are of two kinds, those that are in 



e-4 



Fig 450. Section of a tubule of the testicle of a rat, to show the formation of the sperm- 

 atozoa ; a spermatozoa ; 6, seminal cells ; c, spermatoblasts, to which the spermatozoa are still 

 adherent; d, membrana propria; e, fibro-plastic elements of the connective tissue. (Cacliat.) 



a resting state, which generally form a complete layer, and those that 

 are in a state of division, of which there may be two layers. The latter 

 are called mother cells, and the smaller cells resulting from their division 

 are called daughter cells or spermatoblasts. From these the sperma- 

 tozoa are formed, their head corresponding with the nuclei of the 

 daughter cells; and during their development they lie in groups (figs. 

 449,450), and are supported by irregular masses of so-called nutritive 

 cells; but when fully formed, they become detached, and fill the lumen 

 of the seminiferous tubule (fig. 450). This detachment is effected by 

 the liquefaction of the nutritive cells in which the groups of spermatozoa 

 are imbedded. 



In the fine connective tissue which supports the tubules of the testis, 

 are to be found flattened and nucleated epithelial cells, probably the 

 remains of the Wolflfian body. The lymphatics of the testes are numer- 

 ous, and may be injected by inserting the needle of an injecting syringe 

 into the tunica albuginea, and pressing in the injection with slight 

 effort. 



The Vesiculae Seminales. The vesiculse seminales have the appear- 

 ance of outgrowths from the vasa deferentia. Each vas deferens, just 

 48 



