814 



DEVELOPMENT OF TEE UEO-GENITAL OEGAIs^S. 



single median cavity is produced which lies between the still separate 

 canals of the Wolffian ducts. A large accumulation of tissue in its walls 

 gives to the genital cord great thickness as compared with the neighbour- 



Fig. GOS. 



Pig. 608. — Transverse Sections of the Genital Cord in a Female Calf Embryo. 

 Magnified 14 diameters (from Kolliker). 



1, near the upper end ; 2 and 3, near the middle ; 4, at the lower end ; a, anterior, 

 p, posterior aspect ; m, Miillerian ducts, united or separate ; W, Wolffian ducts. 



ing parts of the ducts where tliey emerge from its enclosure. The lower 

 ]3art of the united Miillerian ducts thus comes afterwards to form the 

 foundation of the vagina and lower part of the uterus in the female, 

 and the corresponding prostatic vesicle with its occasional accompani- 

 ments, or the uterus masculinus of the male. 



REPRODUCTIVE ORGANS. 



In the farther history of the development of the genital organs it 

 will be expedient to consider them in the two sexes in succession under 



Fig. 609. Fig. 609. — Internal Genital Organs op a Male 



Human Embryo of S^ inches long (from Waldej'er). 



t, body of the testicle with seminal canals formed ; 

 c, epididymis, or upper part of Wolffian body ; w, Wolf- 

 fian body, lower part, 1>ecoming paradidymis or organ of 

 Giraldes ; w', Wolffian duct, becoming vas deferens ; ff, 

 gubernaculum. 



the three heads of 1st, the productive 

 organs ; 2nd, the conducting passages ; and 

 3rd, the external organs. 



Keproductive Glands. — It has already 

 been explained that although the male and 

 female productive organs lake their origin 

 fi'om a mass of blastema which is on the 

 whole identical in the two sexes, yet there 

 are such differences in the development ol' 

 the essential parts of the respective structures of the ovary and testicle 

 as almost to warrant the conclusion that these organs are from the firsfc 

 in some measure distinct. 



