The cells of the lower half of the blastosphere are slightly larger than those of the upper half.
Both the blastosphere and gastrula often swim freely by flagella.
While the ovum itself becomes at the same time a blastosphere.
A limit is set to increase in the size of a blastosphere by the nature of the material of its walls.
The cells of the blastosphere may divide themselves by a process of concentric splitting into two layers (fig. 56, 3).
When the egg of Amphioxus is in the blastosphere stage we cannot speak of either an epiblast or hypoblast.
The hollow sphere which is thus formed is the important stage of the “germinal vesicle,” the blastula, or blastosphere.
In the first of these segmentation results in the formation of a blastosphere.
The blastosphere determines the orientation of the gastrula, and so forth.
There is a regular segmentation resulting in the formation of a blastosphere with a central segmentation cavity.