THE URO-GENITAL SYSTEM. 



129 



of enclosing cells and these produce the spermatoblasts. The 

 tunica albuginea is formed from the mesoblastic covering of 

 the genital ridge. The visceral layer of the tunica vaginalis on 

 the testicle is the covering of germinal epithelium which remains 

 after the ingrowth of the genital cells. The vasa efferentia and 

 coni vasculosi are formed from the genital Wolffian tubules. 

 The tubuli recti' and rete testis are new formations. The 

 epididymis is the elongated upper segment of the Wolffian duct 

 (Figs. 82, 107). The Wolffian elements (see p. 102) are produced 

 within the Wolffian ridge. 



Formation of the Gubernaculum Testis. — As shown in Fig. 

 102 there is no trace of the inguinal canal in the 3rd month; 



plica uascularis 

 testis 



pas. deferens, 

 epigastric 



umbilical artery 

 bladder 



gubernaculum 



gubernaculum 

 scrotum. 



Fig. 103. — Showing the Position of the Testis at the 6th month, and the Formation of 

 the Gubernaculum Testis. 



the various layers of the abdominal wall are unbroken. In the 

 fourth month the deep muscular layer of the abdominal wall, 

 composed of the internal oblique and transversalis, buds inwards 

 and expands the plica gubernatrix with muscular and fibrous 

 tissue. The tissue does not stop short at the uro-genital ridge 

 and Miillerian duct as in the female, but grows up and seizes the 

 caudal pole of the testis (Fig. 103). At the same time the 

 tissues in the whole thickness of the abdominal wall bud obliquely 

 inwards towards the scrotum. They are probably carried away by 



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