GENERAL ZOOLOGY 







• • • 



• 



% • « t ,Y 







Mesonephric 

 tubules 



Cartilage 





Fig. 5.30. Differentiation of reaggregated 

 dissociated cells of chick embryo. A, dis- 

 sociated cells of wing bud; x720. B, 

 reaggregated mixture of dissociated cells of 

 mesonephros and wing bud of 3-day chick 

 embryo; x90. C\ mesonephric tubules and 

 cartilage differentiated in reaggregated 

 mixture, as in B, cultured for 10 days; x79. 

 (From J. P. Trinkaus and P. W. Groves, 

 Proceedings of the National Academy oj Sciences, 

 vol. 41, copyright 1955 by University of 

 Chicago Press, reprinted by permission.) 



is normal. If any condition in this group is abnormal, the orderly sequence 

 of developmental processes will be disturbed. Relations between nucleus and 

 cytoplasm, cell mass and cell mass, embryo and external environment can be 

 varied but slightly if a normal individual is to develop. In the developing 

 animal, as in the adult, the cells carry on metabolism if certain conditions 

 are normal. The cells are also responsive and react not only to changes in 

 neighboring cells but also to environmental changes external to the embryo. 



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