156 THE PHYSIOLOGY OF REPRODUCTION 



seen in the chromatolytic changes in the epithelium. 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 follicular 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 foUicle which 

 has faile'd to rupture. Loeb * has described folhcular atresia 

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



The degenerative changes which such folUcles pass through 

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

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

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



' Sobotta.. loc. cit. 



' Van del" Stricht, Vne Anomalie intercssante de Formation de Corps Jaune, 

 Gand, 1901. 



" Loeb (L.), " tJber hypertrophisohe Vorgiinge bei der Follikelatresie," 

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



'' Schnlin, " Zur Morpbologie des Ovariums," Arch. f. Mikr. Anat., vol. xix., 

 1881. 



' Flemming, " Ueber die Bildung von Richtungsfiguren in Saugethieren 

 beim Uutergang Graafsohen FoUikel," Arch. f. Anat. u. Phys.,Anat. Abth., 1885. 



* Schottlander, " Beitrag zur Kenntniss der Follikelatresie," &c., Arch. f. 

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

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



' Henneguy, " Recherches sur I'Atresie des FoUioules de Graaf," &o., 

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



^ Janosik, " Die Atrophie der FoUikel," Arch. f. Mikr. Anat., vol. xlviii., 

 1896. 



° KoUiker, " Uber Corpora Lutea Atretica bei Saugethieren," Yerhand. 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 wahrend der Schwangersohaft," &c., Arch, 

 f. Oynak., vol. Ixxvii., 1906. 



