SEASONAL-VARIATIONS IN THE PRODUCTION OF THE EGG-JELLY MACROMOLECULE,A FUCOSE SULFATE GLYCOCONJUGATE, BY THE ACCESSORY CELLS IN THE OVARY OF THE SEA-URCHIN HEMICENTROTUS-PULCHERRIMUS

In the sea urchin Hemicentrotus pulcherrimus, the egg-jelly macromolec ule, a fucose sulphate glycoconjugate (FSG) that induces the acrosome reaction in spermatozoa, originates from the accessory cells in the ov ary. In the present study we examined the seasonal variations in the d istribution of FSG in the ovary by immunocytochemistry with a polyclon al antibody. An enzyme-linked immunosorbent assay indicated that FSG w as present in supernatants of extracts of ovaries throughout the devel opment of the ovary. However, the immunohistochemical study showed tha t there are marked seasonal changes in the distribution of FSG in ovar ies. The polyclonal antibody reacted strongly with globules of accesso ry cells before the beginning of the breeding season (August to Decemb er). During the breeding season (February to April), the immunohistoch emical reaction was found on the surface of oocytes but was weak in th e accessory cells. At the ultrastructural level, the antibody reacted with globules of variable density in accessory cells. Intense immunola belling was observed in the vacuole-like structures of the globules. S ometimes, products of the specific immunocytochemical reaction were fo und in the Golgi apparatus in these globules. Quantitative examination indicated that FSG was actively produced by the accessory cells from the late non-breeding season to the pre-breeding season. These results suggest that there are marked seasonal variations in the production o f FSG by the accessory cells in the sea urchin ovary. These findings a lso provide new evidence that accessory cells exhibit dynamic changes during the reproductive process in the sea urchin.