ORGANIZING ASPECTS OF GAMETOGENESIS 



317 



Fig. 10. Early oogenesis in the chimpanzee Pan panisciis. Serra fixation, Unna-Brachet 

 stain, (a) Primary follicle in which the follicular cells are enveloping the oocyte (see also 

 the primary unilateral location of the follicular cells in Fig. 3, p. 309). Polarity is still 

 undistinct. The region near the thicker follicular layer is slightly more basophilic, (b) A 

 young secondary (2-layered) follicle showing the corresponding thicker zone; polarity is 

 acquired, the cytoplasm being slightly denser and more basophilic at the animal pole and 

 on the side of the thicker follicle wall. Orig. material gathered in the Belgian Congo by 



Professor G. Vandebroek. 



is of variable thickness and is often crowded with mitochondria, should not be 

 confused with the plasmolemma ; the latter is the thin, homogeneous hyaline layer, 

 enveloped more or less closely by the chorion, which is a secretion of the egg 

 cell. Under higher power (electron microscope) the plasmolemma often shows 



Literature p. 483 



