542 



MANUAL OF HISTOLOGY. 



tion. Its sp. gr. in the human female is, according to Krause and Fischer, 

 1 '045. Chemical analysis, on the other hand, of the ova of the mam- 

 malia is not practicable, owing to the minuteness of the objects to be 

 dealt with. 



REMARKS. See Waldeyers beautiful monograph, "Eierstock und Ei," Leipzig, 

 1870. The best work which has, up to the present, appeared on the subject. 



278. 



Having in the foregoing section become acquainted with the structure 

 of the ovary, let us now take up the question, Whence are the follicles 

 with their cellular contents, and especially the ovum ? For an answer to 

 this query we shall be obliged to follow up the development of the 

 organ. 



The following is the view which obtains most generally in regard to 

 the origin of the ovary. 



The germ-preparing glands of the female spring from the sides of those 

 temporary urinary glands of the embryo known as the Wolffian bodies. 



The epithelial covering of the Wolffian bodies is observed very early to 

 undergo a thickening at the spot in question in the embryonic chicken 

 (Waldeyer). At the same time a small cellular growth makes its appear- 

 ance here also, springing and projecting from the connective-tissue mass 

 of the organ. 



Now, from the thickened epithelium covering this projection the rudi- 

 ments of the Graffian follicles and ova are formed, as well as the later 

 ovarial epithelium, while from the connective-tissue the vascular susten- 

 tacular substance of the organ takes its rise. 



The epithelial clothing is soon observed to contain (not only in the 

 chick, but also in the mammal embryo) certain enlarged cells or primor- 

 dial ova. 



The further changes consist in an intermixture of the fibrous and epi- 

 thelial constituents. Fig. 534 gives a representation of what now takes 



Fig. 534. Vertical section of the ovary of a human foetus 32 weeks old (after Waleteuer). a, 

 germinal epithelium; 6, younger egg-cells, the "primordial ova" contained in this; ^in- 

 growing band of fibrous connective-tissue; rf, epithelial cells in process of being folded 

 in; e, youngest follicles; /, ova and germinal epithelial cells in groups; g, lymphoid cells. 



place. The connective-tissue processes increasing rapidly in length, the 

 aggregations of cells become smaller and smaller, and contain one or 



