

Microns 



Figure 305. — Photomicrograph of an unfertilized egg of C. virginica. Janus green. Whole mount. Small rodlike 

 inclusions seen along the periphery are mitochondria stained green; larger yolk granules are dark. 



Allen, 1953; and Rebhun, 1960). The role of 

 these almost submicroscopical bodies is not clear, 

 but there is no doubt of their importance in the 

 physiology and development of eggs. Recent 

 publications of Dalcq (1960), Brachet (1960), and 

 Rebhun (1960), and the reviews given by NovikofT 

 (1961a, 1961b) should be consulted for ideas con- 

 cerning the possible role of these elements in the 

 morphogenesis of mosaic eggs in which they are 

 concentrated in the posterior blastomeres. 



Eggs of the surf clam S. solidissima contain a 

 heparinlike blood anticoagulant which was also 

 extracted from the tissues of this clam (Thomas, 

 1954). Whether substances with sunilar activity 

 are present in oyster eggs is not known. 



The nucleus of a mature egg is surrounded by a 

 nuclear membrane which can be clearly seen on 

 sectioned and stained preparations of the ovary 

 (fig. 300). A spherical, dense nucleolus is excen- 

 trically located; its diameter varies from 4 /i to 6 m- 



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FISH AND WILDLIFE SERVICE 



