Newport and Kirschner described a "transition" that occurs at the middle of this stage where transcription of zygotic genome begins and the cell cycle lengthens.
The "chordin" and "noggin" expressing centers in this structure contain cells which are precursors to Spemann's organizer cells, and the motility of cells during this stage may be classified as cavitation or ingression. Newport and Kirschner described a "transition" that occurs at the middle of this stage where transcription of zygotic genome begins and the cell cycle lengthens. The transition to its subsequent stage involves the formation of the endoderm, ectoderm, and mesoderm, and it sees a layer of cells forming a hollow sphere which encloses fluid called the blastocoel. For 10 points, identify this stage of development which precedes the gastrula.
The "chordin" and "noggin" expressing centers in this structure contain cells which are precursors to Spemann's organizer cells, and the motility of cells during this stage may be classified as cavitation or ingression.
{blastula}