CIL:39791

Scanning electron microscope image of Strongylocentrotus drobachiensus [sea urchin] embryo at the late gastrula stage. This high magnification image of the embryo shows the primary mesenchyme syncytial ring, where it attaches to the outer epithelial layer (ectoderm layer). The fine fibers are part of the blastocoel matrix. The primary mesenchyme syncytial ring is the precursor to spicule formation (developing calcareous larval skeleton). 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.