coelom 



ORIGIN OF DEFINITIVE SEX-CELLS 



alb 



Koog. 



465 





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c. 



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c. c. med. 



Fig. 8 Portion of a transverse section through ovary of a 14-day chick embryo. 

 The groups of oogonia, resulting from division of the primodial germ-cells, now 

 extend down into the medulla as cortical cords. The oogonia produce the de- 

 finitive ova and the follicular cells the follicular epithelium. 



The ovary of the 10-day chick closely resembles that of the 

 9-day chick, which has just been described. 



The oogonia are still dividing, regular nests of mitoses are 

 seen occasionally, in which 3 to 6 cells may be seen dividing at 

 the same time. The lobulations on the deep surface of the germ- 

 inal epithelium have increased in size, due of course to the 

 increased number of oogonia. These lobulations are now quite 

 distinct from the germinal epithelium, to which they are at- 



