One-half of the blastosphere may be pushed in towards the other half.
The blastosphere determines the orientation of the gastrula, and so forth.
Both the blastosphere and gastrula often swim freely by flagella.
The blastosphere, growing beyond its limits, folds into a cup-shaped organism.
While the ovum itself becomes at the same time a blastosphere.
The hollow sphere which is thus formed is the important stage of the “germinal vesicle,” the blastula, or blastosphere.
A limit is set to increase in the size of a blastosphere by the nature of the material of its walls.
When the egg of Amphioxus is in the blastosphere stage we cannot speak of either an epiblast or hypoblast.
The central part of the blastosphere is called the segmentation cavity or blastocoel.
The cells of the blastosphere may divide themselves by a process of concentric splitting into two layers (fig. 56, 3).