Name: blastopore formation stage
ECAO ID: 0000380
Definition: "The embryo is characterized morphologically by a slight invagination of the vegetal plate and the dispersal of the skeletogenic primary mesenchyme cells (PMCs) along the blastocoel wall at the periphery of the invaginating region. The PMCs are just beginning to adopt a characteristic, ring-like arrangement near the equator of the embryo. Within the vegetal plate, the peripheral non-skeletogenic mesoderm cells have started to indent, undergoing important cell shape changes, but the center of the vegetal plate (composed of small micromeres) has not started to elevate. Invagination has generated the blastopore (an opening that will give rise to the larval anus) as well as the anterior portion of the archenteron (a region that will give rise to the coelomic pouches). At the animal pole, the apical pole domain is still marked by an enlarged epithelium bearing long and immotile cilia."
|
|
