514 Animal Biology 



The testes contain many seminiferous tubules which produce sperm 

 (spermatozoa) by a proHferation of the spermatogonia cells (Fig. 351) 

 which line the tubules. The number of sperm discharged at one time 

 may be about two hundred million suspended in a small amount of 

 seminal fluid (semen). The latter is secreted by the seminiferous tubules, 

 epididymis, vas deferens, and primarily by the prostate and Cowper's 

 gland. The sperm is extremely small and has a globular head with a 

 nucleus, a neck, and a slender tail of cytoplasm (Fig. 223) . 



Ureters 



.Bladder 



Fig. 254. — Reproductive organs of human (male) 



diagrammatic. 



Seminal vesicle 



Prostate gland 

 Cowper's gland 



Vas deferens 

 Urethra 



Epididymis 



Teistis 



Scrotum 

 Side view and somewhat 



The human female reproductive system (Fig. 255) consists of (1) the 

 pair of oval ovaries in the lower abdominal cavity and (2) the pair of 

 Fallopian tubes (oviducts) the anterior ends of w^hich are funnel shaped 

 and lie near the ovary; the anterior opening of the tubes is the ostium 

 (infundibulum) which picks up the ovum (egg) (Fig. 223) produced 

 and liberated by the ovary; the Fallopian tubes carry the ovum to the 

 pouchlike uterus in which the embryo develops; (3) the vagina which 

 connects the uterus with the exterior. The walls of the uterus contain 

 smooth muscles which contract vigorously under certain conditions, such 

 as childbirth. The inner lining of the uterus, called the endometrium, 



