Egg jelly

Egg jelly is a gelatinous layer that surrounds the oocytes of many organisms and releases species-specific chemoattractants that activate and guide sperm to the oocyte. The release of chemoattractants is species dependent. For example, sperm in Lytechinus variegatus, the green sea urchin, are not chemotactically attracted to the jelly or the egg. The egg jelly is located immediately surrounding the vitelline envelope and consists primarily of a network of short peptides and sulfated fucan glycoproteins. These short peptides diffuse into the surrounding area and stimulate respiration and movement of the sperm to the egg. An example of such a peptide is resact, which has been studied as the primary means of attracting and orientating sperm to the eggs in sea urchins. The sulfated fucan glycoproteins play an important role in binding to sperm receptors and triggering the acrosomal reaction.

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