Oviduct 



Testis 



Efferent 

 duct 



Ureter 



and 

 sperm 



duct 



Seminal 

 vesicle 



Reproductive system 

 of female frog 



Reproductive system 

 of male frog 



REPRODUCTIVE ORGANS OF THE FROG 



Eggs discharged by the ovaries into the 

 body cavity get into the funnel-lil<e open- 

 ing of coiled egg tube. Eggs become 

 covered with gelatinous substance se- 

 creted by lining cells of the oviduct. Past 

 the thin-walled enlargement of the ovi- 

 duct, called the uterus, eggs leave body 

 by way of the cloaca 



The sperms are formed by cells lining the 

 fine tubules that make up the spermary, 

 or testis. The sperm cells float in the 

 spermatic fluid, or semen. The semen is 

 gathered into a duct that joins the urine- 

 conducting tube from the kidney (the 

 ureter), and is then discharged from the 

 body by way of the cloaca 



as insects, deposit eggs that hatch outside the mother's body, after they are 

 fertilized inside the body. 



Reproduction in Mammals^ In mammals, including man and the other 

 primates, the paired ovaries and testes develop from early budding of the 

 endoderm into what later becomes the body cavity. As in all vertebrates, the 

 gonads originate early in the embryo's development in close association with the 

 kidne)'s. But the ovaries and the testes are complex organs: in addition to 

 their gamete-producing functions, they produce special hormones, or endo- 

 crines (see page 314). In the males of nearly all mammals the testes change 

 their positions in the abdominal cavity, gradually descending into a pouch, 

 or bag, which extends outside the body wall. This is called the scrotum. 



The ovaries consist of masses of cells that produce eggs only near the sur- 

 face. The core of the ovary contains cells that produce the specific "female 



iSee No. 9, p. 396. 

 379 



