CHANGES IN THE OVARY 151 



hypertrophying, degenerates, the chromatic substance at one stage 

 often appearing in the form of fine points in the cytoplasm, and 

 much smaller than nuclei. Subsequently the remains of the cells 

 become unrecognisable, finally disappearing altogether. (4) The 

 connective tissue wall does not proliferate to form a network among 

 the epithelial cells, and there is generally no ingrowth from the 

 thecse until the epithelial cells are in an advanced state of degenera- 

 tion or have altogether disappeared. The earliest indication of atretic 

 change is usually 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 instances 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 ease of retention in Vesperugo, in which part 

 of the follicle was degenerate 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 follicular atresia as being common 

 in guinea-pigs of less than six months old. Kingsbury * has described 

 profound degeneration of certain follicles as occurring just before 

 sexual maturity in the cat. Atrophic follicles which have reached or 

 almost reached maturity (in the rabbit) before undergoing degenera- 

 tion are characterised by a considerable internal hsemorrhage. 



The degenerative changes which such follicles pass through have 

 been studied in various Mammalia (chiefly rabbits, cavies, and other 

 Eodents) by Schulin,^ Flemming,^ Schottlander,' Henneguy,* Janosik,® 



' Sobotta, loo. ait. 



^ Van der Stricht, TJne Anomalie interessante de Formation de Corps Jaune, 

 Gand, 1901. 



^ Loeb (L.), "Uber hypertrophische Vorgange bei der FoUikelatresie," Arch. 

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



* Kingsbury, " The Morphogenesis of the Mammalian Ovary," Amer. Jour, 

 of Anat., vol. xv., 1914. 



^ Schulin, "Zur Morphologie des Ovariums," Arch. f. Mikr. Anat., vol. xix., 

 1881. 



" Flemming, "Ueber die Bildung von Richtungsfiguren in Saugethieren 

 beim Untergang G-raafschen FoUikel," Arch. f. Ariat. u. Phys., Anat. Abth., 1885. 



' Schottlander, " Beitrag zur Kenntniss der FoUikelatresie, etc.," Arch. f. 

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

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



* Henneguy, " Recherches sur I'Atrfesie des FoUicules de Graaf, etc.," Jour, 

 del' Anat. et de la Phys., vol. xxx., 1894. 



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

 1896. 



