456 



THE REPRODUCTIVE SYSTEM 



ducts, glands and appendages; and an external genital organ, the penis 

 (Fig. 418). The FEMALE ORGANS OF REPRODUCTION likewise include an 

 internal group of genitalia, namely, the ovary, with its ducts and the 



FIG. 419. DIAGRAM OP FEMALE INTERNAL GENITALIA. 



associated glands and appendages; and a group of external genitalia 

 and glands (Fig. 419). The essential sex organs are the testis and ovary, 

 respectively. 



DEVELOPMENT 



The primary anlages are the same in both sexes. They include essen- 

 tially : a pair of undifferentiated sex-glands or gonads located on the mid- 

 ventromesial side of each fetal kidney (Wolffian body or mesonephros) ; a 

 double pair of parallel canals, the fetal Wolffian (mesonephric) ducts and 

 the Miillerian ducts. An embryo at this stage of development (13 milli- 

 meters, Fig. 210, about 40 days) is said to be in the indifferent sexual stage. 

 The ducts communicate terminally with the gonads and the exterior. Sub- 

 sequently they undergo a different development, as do also the terminal 

 associates (gonads, and urogenital sinus, respectively) in the two sexes. 

 For the details of this process reference must be made to a text-book of 

 Embryology. But briefly, the primitive gonads in the female develop into 

 the ovaries, in the male into the testes. In the female the Miillerian ducts 

 become the oviducts, and fuse proximally to form the uterus and vagina; 

 in the male, this duct suffers regressive changes and persists only as ves- 

 tiges : the appendix testis, and the sinus pocularis. On the contrary the 

 Wolffiaii duct becomes vestigial in the female, persisting as the appendix 

 fimbria (hydatid of Morgagni) and the canal of Gartner; while in the male, 

 it develops into the main portion of the definitive duct system : ductus epi- 

 didymis, and ductus deferens. The tubules of the fetal kidney (Wolffian 



