Regenerative Capacity of Ovarian Tissue 39 



changes could not possibly run their course in the way they 

 do if the germinal epithelium was not able to proliferate (see 

 also Schmidt and Hoffman, 1941; and Schmidt, 1942). 



Other kinds of evidence bearing on the question of oogenesis 

 are referred to by Aron et al. in a non-critical, or at best non- 

 committal way, and apart from certain comments which are re- 

 ferred to below, these authors do not resolve the contradictions 

 posed by the work done in my own laboratory to the thesis 

 they support. They proceed to deal with the field of observation 

 in which they themselves have contributed. This concerns the 

 occurrence in the ovaries of the mature lemur, the armadillo 

 and the guinea pig, of nuclear changes which are suggestive of 

 the division of oocytes. The lemurs can be usefully considered 

 first, as they were the first to be described in this connection 

 (Gerard, 1919/20; Rao, 1927; and Gerard and Herlant, 1953). 



The observations of Gerard (1919/20) and Gerard and 

 Herlant (1953) relate to adult specimens of the African Loris- 

 idae (Galago senegalensis moholi, G. crassicaudatus, G. demidoffi 

 and Perodicticus potto). In all these species "oogenetic cords" 

 containing primordial oocytes are found separated from the 

 germinal epithelium by a tunica albuginea of varying thick- 

 ness. Many of the cells in these cords are actively dividing, 

 and according to Gerard and Herlant can be regarded only as 

 oogonia. Other cells show chromatin configurations charac- 

 teristic of the leptotene, synaptene and pachytene stages of 

 meiosis. Cells corresponding in all cytological respects with 

 oogonia were also recognized in the germinal epithelium 

 itself. 



Rao (1927) studied the Indian species Loris lydekkerianus, 

 and noted that "tubular" invaginations of the germinal 

 epithelium ramify in certain parts of the ovary of the pregnant, 

 but not non-pregnant, adult. Rao was under the impression 

 that it had been firmly established that oogenesis in mammals 

 continues throughout adult life, and he therefore tried to 

 decide whether oocytes are formed from invaginations of the 

 germinal epithelium, or as Lane-Claypon had suggested in the 

 case of the rabbit, from the interstitial cells of the ovary as 



