THE vertebrates: the amphibia and birds 



147 



Z.VEG. 



Figure 9.1 



Ooplasmic regions of the unfertilised egg oiXenopns. The main regions are': 

 the animal region [Z.AN.); the marginal zone {Z.M.); the central region 

 (AT.C.) and the vegetative region (Z.Veg.). The upper drawing shows the 

 location of these in a transverse section, while the lower drawings illustrate 

 the nature of the cytoplasms. (From Pasteels 195 1.) 



