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.
Biological Process: Embryonic morphogenesis
Images taken on a JEOL 35C SEM.
1. 2% GTA in 75% MBL SW or FilteredSW
FSW - fix for 1.5hrs. RT.
2. Rinse with 0.1M NaCacodylate buffer pH 7.4
3. 0.5% OSO4 in .075M NaCacodylate buffer pH 7.4 - 30' in the cold
4. Rinse in 0.1M NaCacodylate buffer ph 7.4
5. Dehydrate thru ETOH: 30%, 50%, 70%, 95% for 5 min each
6. 100% - 3 changes - 15' each
7. Critical Point Dry
8. Stick embryos down onto silver paint. Gently crack open with glass needle (pipette drawn out to a fine point).
9. Sputter coat with AuPd.
Author: Louisa Howard
Source: The Cell: An Image Library