Invertebrate
Zoology Sea Urchin Embryology Lab
Species: Eucidaris tribuloides
Observing fertilization
and development of fertilization membranes
1. To observe fertilization and development of the fertilization membrane, place a drop containing eggs on a slide and cover with a cover slip (you can also try a depression slide).
2. Add a drop of sperm suspension to the edge of the cover glass so it comes in contact with the water in the egg suspension. The sperm will diffuse under the cover slip and the events of early fertilization can be observed. The sperm should be added to the slide after it is positioned on the microscope stage, as fertilization can occur within 30 seconds of sperm contact.
The first division should
begin about 80 minutes after adding the sperm suspension. Development of the eggs will continue
through a series of divisions. The
blastula stage can usually be observed in 18 to 24 hours, early gastrula in 30
to 36 hours, and early pluteus (larvae) in 72 to 80 hours. Development time can vary slightly because
of difference in conditions in the laboratory.