CIL:39788

Scanning electron microscope image of Strongylocentrotus drobachiensus embryo at the primary mesenchyme blastula stage. Embryo was split open to reveal the outer epithelial layer and the blastocoel cavity at the vegetal pole. At this stage of embryonic development, primary mesenchyme cells are forming (flask shaped cells in the epithelial layer) and beginning to migrate into the blastocoel cavity. 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.