Caption

Scanning electron microscope image of Strongylocentrotus drobachiensus [sea urchin] embryo at the late gastrula stage. Embryo was cut to reveal blastocoel cavity. The fertilization envelope dissolves during swimming blastula stage; therefore, the cilia and microvilli can be seen on the outer epithelial layer. The primary mesenchyme cells have formed a syncytial ring, which is the precursor to spicule formation(developing calcareous larval skeleton). A portion of the archenteron can also be seen.

Class Echinoidea

Superorder Echinacea

Order Echinoida

Strongylocentrotus drobachiensus

JEOL 35C SEM

Writer

Louisa Howard

Keywords

marine invertebrate, SEM, sea urchin, embryo