SOME STUDIES ON DIFFERENTIATION AND 

 DEVELOPMENT OF THE OOCYTE "" 



W. S. VINCENT: upstate medical center, 



STATE UNIVERSITY OF NEW YORK, 

 SYRACUSE, NEW YORK 



When one considers the development of the oocyte, it becomes 

 apparent that there are two general problems to be studied. One 

 of these is the problem of the origin of the egg cell; the other, that 

 of its later development. 



The study of the origin of the primary germ cell, from which 

 the oocyte is derived, has provoked wide interest and consider- 

 able controversy. Out of this has arisen the following questions: 

 Is there a separate germinal plasm which gives rise to the pri- 

 mordial germ cells, these in turn migrating to the gonad and 

 there forming definitive gonia; or do some or all of the definitive 

 germ cells arise from somatic cells of the germinal epithelium? 

 In some invertebrates it is readily observed that the functional 

 germ cells are derived from a line of cells set apart veiy early in 

 development, although in the coelenterates and annelids this 

 early setting apart is still questionable ( Berrill and Liu, 1948; Wil- 

 son, 1928). In vertebrates, and especially mammals, the evidence 

 for the origin of the definitive germ cell from a primary cell type 

 is far from being conclusive. Although there is general agreement 

 that a primordial germ cell type is found, there is disagreement 

 as to whether these cells migrate into the gonad and there even- 

 tually dififerentiate into mature oocytes, or whether they degen- 



* Part of the work reported here was done during the tenure of a Ful- 

 bright Fellowship to Belgium. Some of the work was done at the Marine 

 Biological Laboratory, Woods Hole, during the tenure of a Lalor Founda- 

 tion Fellowship, and in addition, while supported by funds from the Atomic 

 Energy Commission, grant AT (30-1) 1343. 



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