156 THE PHYSIOLOGY OF REPRODUCTION 



seen in the chromatolytic changes in the epithehum. Afterwards 

 the theca interna degenerates, and then the ovum and zona 

 pellucida. 



It should be mentioned, however, that the presence of a 

 degenerate ovum cannot, by itself, be regarded as an absolute 

 indication of folhcular atresia, since Sobotta ^ has recorded in- 

 stances of rupture in the mouse and in the rabbit in which the 

 ova were accidentally retained within the cavity of the follicle, 

 the latter nevertheless forming an otherwise typical corpus 

 luteum ; and van der Stricht ^ has described a similar case of 

 retention in Vesferugo, in which part of the follicle was de- 

 generate while another part possessed the characteristic structure 

 of a corpus luteum. 



Degeneration may set in at all stages in the development 

 of a follicle, and not merely in the fully formed follicle which 

 has failed to rupture. Loeb ^ has described folhcular atresia 

 as being common in guinea-pigs of less than six months old. 



The degenerative changes which such folhcles pass through 

 have been studied in various Mammaha (chiefly rabbits, cavies, 

 and other Rodents) by Schuhn,* Flemming,® Schottlander,* 

 Henneguy,' Janosik,^ Kolhker,^ van der Stricht,'" Seitz,'^ Loeb, 



' Sobotta, loc. cit. 



' Van der Stricht, Une Anomalie interessante de Formation de Corps Jaune, 

 Gand, 1901. 



' Loeb (L.), " tjber hypertrophische Vorgange bei der Follikelatresie," 

 Arch. f. Mihr. Anat., vol. Ixv., 1905. 



^ Schulin, " Zar Morphologie des Ovariums," ^rc7i. /. Mikr. Armt., vol. xix., 

 1881. 



^ Flemming, " Ueber die Bildung von Richtungsfiguren in Siiugethieren 

 beim Untergang Graafschen ¥o\\i)i.e\," Arch. f. Anat. u.Phys.,Anat.Abth., 1885. 



^ Schottlander, " Beitrag zur Kenntniss der Follikelatresie," &o.. Arch. f. 

 Mikr. Anat., vol. xxxvii., 1891. " Ueber den Graafschen FoUikel," &c., Arch, 

 f. Mikr. Anat., vol. xli, 1893. 



' Henneguy, " Recherohes sur I'Atresie des Follicules de Graaf," &c., 

 Jour, de I' Anat. et de la Phys., vol. xxx., 1894. 



* Janosik, " Die Atrophic der FoUikel," Arch. f. Mikr. Anat, vol. xlviii,, 

 1896. 



' Kblliker, " Uber Corpora Lutea Atretica bei Siiugethieren," Verhand. d. 

 Anat. Gesell., in Kiel, 1898. 



'" Van der Stricht, "L'Atr^sie Ovulaire," &c., Verhand. d. Anat. Gesell., 

 in Bonn, 1901. 



11 Seitz, "Die Follikelatresie wiihrend der Schwangerschaft," &c., Arch, 

 f. Gynah., vol. Ixxvii., 1906. 



