CIL:39785

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. A high magnification view of a region of this image is available as CIL:39789. This image is part of a group of SEM images of sea urchin embryos at various stages of development. The group is available as CIL:39782-39791.