Penetration of the egg by one sperm induces the cortical granule reaction, and a fertilization membrane
is raised after a few minutes.
For animals that do not display a fertilization membrane
, such as polychaetes, bivalves, and gastropods, fertilization success is sometimes assessed by the ability of eggs to cleave (e.g., Fong et al., 1995; Qiu and Qian, 1997; Ushakova and Sarantchova, 2004).
In this study, chromosome preparations were made from embryos at the early cleavage stages; there was no need to remove the fertilization membrane
, yolk granules, or oil droplets.
The fertilization membrane
and a fertilization cone [ILLUSTRATION FOR FIGURE 2B OMITTED] lift off from the surface of the egg after about 34 min at 6 [degrees] C, leaving a large perivitelline space of 65 [[micro]meter].
Release of ovoperoxidase from sea urchin eggs hardens the fertilization membrane
with tyrosine crosslinks.
After their fertilization, the eggs were attached to one another by the fertilization membrane
, showing that the membrane was sticky, especially after reaching the 2-cell stage [ILLUSTRATION FOR FIGURE 9A OMITTED].
One egg aliquot was immediately assayed to determine the presence of (1) fertilization membranes
, or (2) immature or abnormal eggs.