LIPOVITELLIN AND LIPID DROPLET ACCUMULATION IN OOCYTES DURING OVARIANMATURATION IN THE BLUE-CRAB, CALLINECTES-SAPIDUS

Blue crab ovaries rapidly increased in weight during the 30 days after the terminal molt into adulthood. Oocytes isolated from ovaries durin g this period increased in diameter from 40 to 201 mu m. The concentra tions of lipovitellin, a high density lipoprotein found in oocytes, we re determined by a competitive ELISA procedure using a monoclonal anti body against one of the lipovitellin peptides. Lipovitellin and lipid droplets were minor components in the immature ovaries and oocytes but increased in concentration to become the major components of the matu re ovaries and oocytes. In mature oocytes (201 mu m diameter) lipovite llin concentrations accounted for 35 and 95% of the total oocyte prote in and soluble oocyte protein, respectively. In mature oocytes the tot al lipid, lipovitellin lipid, and lipid droplet concentrations were 51 0, 240, and 140 ng/oocyte, respectively. Sections of ovaries and hepat opancreas at different stages of maturation were probed with the anti- lipovitellin antibody. In small immature oocytes, where no yolk was pr esent, the immunoreactivity was confined to perinuclear yolk complexes . The immunoreactivity of more mature oocytes was associated with glob ular structures in the cytoplasm. Neither ovarian follicle cells nor h epatopancreas cells showed immunoreactivity. Our results suggest that in blue crabs the lipovitellin components are primarily synthesized in the developing oocytes with perinuclear yolk complexes playing an imp ortant role in the formation of lipovitellin-rich yolk granules. Scatt ered collections of presumed phagocytic hemocytes contained immunoreac tive granular material in their cytoplasm. We suggest that these hemoc ytes remove debris from oocytes which fail to reach maturation and car ry this debris to the hepatopancreas. (C) 1995 Wiley-Liss, Inc.