THE ORIGIN OF THE DEFINITIVE OVA 



Schron, 1863 — cat and rabbit; Koster, 1868 — man; Slawin- 

 sky, 1873 — man ; Wagener, 1879 — dog; Van Beneden, 1880 — 

 bat ; Harz, 1883 — mouse, guinea pig, cat; Lange, 1896 — mouse; 

 Coert, 1898 — rabbit and cat; Amann, 1899 — man; Palladino, 

 1894, 1898— man, bear, dog; Lane-Claypon, 1905, 1907— 

 rabbit; Fellner, 1909 — man) save that the work of Allen 

 and those who follow takes advantage of recent discoveries 

 of the nature of the oestrus 

 cycle, and presents observations 

 made upon ovaries taken at def- 

 inite times during the cycle. 

 Since the embryogenesis of the 

 primordial germ cells and the 

 germinal epithelium are separate loo — 

 and distinct it follows from the 

 findings of these observers that 

 the definitive ova of adult hfe 

 do not arise from the primordial 

 germ cells at all. Most of the 

 earlier workers observed evi- 

 dences of growth and thickening Fig. l. The frequency of mi- 



of the germinal epithelium or r^^rttiaTa'cf AUe"! 



even extensions of germinal epi- 1923. Open circles indicate com- 



thelium into the ovarian cortex. ^^,f ^^^^ on semi-spayed mice. 



Halt circles mdicate normal un- 

 In some cases these signs of operated controls. Abscissae are 

 activity were associated with stages of oestrus cycle; l, early pro 



the period of heat. 



Allen (1923) whose investiga- 

 tions are perhaps pioneer to 



the most recent developments mitoses per mouse. (From the 

 distinguished four stages in the ^^nerican Journal of Anatomy.) 



behavior of the germinal epithelium of the adult mouse 

 during the oestrus cycle. The first, characterized by ex- 

 tensive mitotic activity occurs just before and during oestrus 

 (see Figure 1). The second is marked by a fairly abrupt 

 decrease in mitosis frequency, and a position of the daughter 

 epithelial cells one cell layer below the germinal epithehum 



oestrus; 2, late prooestrus; 3, pro- 

 oestrus to oestrus; 4, early oestrus; 

 5, oestrus; 6, early metoestrus; 

 7, metoestrus; 8, dioestrus. Or- 

 dinates are average number of 



