338 



REPRODUCTION 



.is taken by some of the cells of the inner layer. This second 

 surrounding layer is the epiblast, or ectoderm; the surrounded 

 mass is the hypoblast, or entoderm. 



ent. 



FIG. 96. Sections of the ovum of a rabbit, showing the formation of the 

 blastodermic vesicle. (From Yeo after E. Van Beneden.) 



a, b, c, d, are ova in successive stages of development; Z, p, zona pellucida; ect, 

 ectomeres, or outer cells; ent, entomeres, or inner cells. 



Before long the entoderm spreads out over a larger area, and 

 from it and from the ectoderm is developed a layer of cells, the 



