808 



DEVELOPMENT OF THE UEO-GEXITAL OEGAXS. 



a manner somewhat different. Both are mainly produced in the sub- 

 stance which lies along the inner border of the blastemic mass already- 

 referred to, and which may therefore be named the common reproductive 

 blastema ; but with this important difference between them, that in the 



Fijr. C04. 



Fig. G04. — Transverse Section op the Wolffian Body and Rudiment of the Ovary 

 AND THE Duct op Muller in an Embryo Chick at the end of the fourth 

 DAY (from Waldeyer). 



WK, Wolffian body ; y, section of the Wolffian duct ; a, germ epithelium with, o, o, 

 cells enlarging into ovigerms ; a', epithelium near the place of involution of MviLler's 

 duct, z ; E, stroma of the ovai-y ; m, mesentery ; L, lateral wall of the abdomen. 



female the primitive ova originate more immediately from the cells of 

 the surface in the germ ejntlieUum, and become afterwards imbedded 

 as Graafian follicles in the deeper substance of the mass which forms a 

 stroma round the ova ; while the glandular substance of the testicle is 

 apparently developed within the cell mass, without any direct con- 

 currence of the superficial or germ epithelium, — which, though at first 

 existing in male as well as in female cmbryoes, and even exhibiting 

 some tendency to the enlargement of some cells as ovigerms (Waldeyer), 

 soon becomes atrophied and reduced in thickness in the male as the 

 structure of the testicle becomes developed. 



The ducts of Muller open at their anterior extremities into the 

 pleuro-peritoneal cavity by the orifice which ultimately becomes the 

 infundibulum and fimbriated ostium abdominale ; and, as their lining 

 membrane has originally been formed by an involution of the epithelium 

 (germ-epithelium) of that cavity, it follows that the lining membranes 

 of the female passages (Fallopian tubes and uterus) which in their later 

 development assume the characters of mucous membrane, and are de- 



