

DEVELOPMENT OF THE OVARIES AND OVA. 



197 



(52), Langhans (64), and Kolliker (59), have been equally unsuccess- 

 ful. It is absent also, as we have remarked, in the follicles of 

 Mammals ; but, on the other hand, it is present at a later stage in the 

 larger follicles of Birds (see fig. 194). During the dividing off of 

 the follicles the egg cells remain for a time connected by means 

 of their protoplasm, whilst the epithelial cells near the points of 

 mutual attachment or poles of the follicle, after the complete sepa- 

 ration of the latter, are characterized by their small size. 



Fig. 198. 



Fig. 198. Part of a vertical section of the ovary of a new-born 

 Infant (Hartnack 3-7), with shut-up tube, a, Epithelium of the 

 ovary ; 6, rudiment of an ovarial tube ; c c, ova lying in epithelium ; 

 d, longer ovarial tube, with incipient formation of folh'cles ; e e, 

 egg balls, also with commencing follicular formation ; /, youngest 

 already completely isolated follicle ; g g, vessels. In the tubes and 

 egg balls the primordial eggs and the smaller epithelial cells, consti- 

 tuting at a later period the follicular epithelium, are to be distin- 

 guished. 



According to the statements of Pfliiger, the tubes lying close be- 

 neath the surface of the ovary terminate by caacal extremities, and in 

 these the germinal vesicles originate, surrounded by a diffuse proto- 

 plasm that forms a more definite investment for each as they be- 

 come more deeply situated with the tube. Thereupon a number of 

 these cells become conspicuous by their more vigorous growth, whilst 

 the rest remain unaltered, and form the epithelial lining of the tubes. 



