MULTICELLULAR ANIMALS 



199 



their circulatory and mesenteric connections with their primitive 

 position in the anterior region of the peritoneal cavity. 



Reproductive System of the Human Male. The human 

 testis (Fig. 136) consists of a considerable number of contorted 

 SEMINIFEROUS TUBULES that lead into a series of ducts known as the 

 RETE TESTIS. The rcte tubules communicate with another set of 

 tubes, the vasa efferentia, derived from the mesonephric tubules: 



SPERMATIC CORD 



VAS DEFERENS 



VASA EFFERENTIA 



EPIDIDYMIS 



EPIDIDYMIS DUCT- 



TEST IS 



SEPTUM 



SEMINIFEROUS 

 TUBULE 



SCROTUM 



Fig. 136. — A partially dissected human testis and a diagram showing the rela- 

 tions of its parts. (Partly after Sobotta: Atlas and Textbook, of Human Anatomy, 

 published by W. B. Saunders Co.) 



the vasa efferentia deliver their contents into the single main duct, 

 the vas deferens, the mesonephric duct of lower forms. The vas 

 deferens is joined near the base of the urinary bladder by a sac 

 termed the seminal vesicle and also receives the duct from a large 

 PROSTATE GLAND. The vas deferens then empties into the urethra. 

 In this region the vas deferens is called :he ejaculatory duct. The 

 urethra thus serves a double function, an outlet from the urinary 

 bladder and an outlet for the products of the testes. 



The long, contorted seminiferous tubules in the testes are the 

 site of origin and of maturation of the spermatozoa. The walls of 



