Long-lasting exocytosis and massive structural reorganisation in the egg periphery during cortical reaction inPlatynereis dumerilii(Annelida, Polychaeta)

SummaryThe course of the cortical reaction in thePlatynereis dumeriliiegg is described from live observation and from sectioned fixed material and is found to differ in several aspects from the course of cortical reactions in better-known systems. Cortical granules are unusually numerous. They are discharged by exocytosis during a period of about 25 min following fertilisation (18°C). Most of the surplus membrane material brought to the egg surface by exocytosis is set free into the perivitelline space. Swelling of egg jelly precursor secreted by cortical granule exocytosis may be causal for the detachment of the vitelline envelope from the egg cell surface which, however, remains attached …