842 



SPERM, OVA, AND PREGNANCY 



Fig. 14.14. Migration of the male and female prouuclei towards the center of the egg, 1 and 

 2. The male pronucleus is frequently indented by the female pronucleus, 2. At 3, note the dis- 

 appearance of the nucleoli in the pronuclei immediately before the appearance of recognizable 

 chromosomes as seen in 4. Telophase stage during first segmentation division in 5. PB, polar 

 body (Odor and Blandau, 1951). 



(Lams, 1913) ; rat (Gilchrist and Pincus, 

 1932; Austin, 1951b; Blandau and Odor, 

 1952) ; and ferret (Mainland, 1930). Pineus 

 (1930) and Nihoul (1926) were not con- 

 vinced that in rabbits the flagellum enters 

 the ooplasm. In the vole the flagellum enters 



the vitellus in only 55 per cent of fertilized 

 eggs (Austin, 1957). 



Except for the investigations by Gresson 

 in the mouse, and Blandau and Odor in the 

 rat, there are no detailed accounts of the 

 fate of the flagellum after it enters the fer- 



