IMMUNOCYTOCHEMICAL IDENTIFICATION OF THE SITE OF VITELLOGENIN SYNTHESIS IN THE FRESH-WATER PRAWN MACROBRACHIUM-NIPPONENSE

The site of vitellogenin synthesis in the freshwater prawn Macrobrachi um nipponense was examined immunocytochemically using antibodies raise d against lipovitellin purified from mature M. nipponense ovaries. The molecular weight of purified lipovitellin was estimated to be 350 kDa by gel filtration. The antiserum cross-reacted with vitellogenin in t he hemolymph of the mature female prawn, and could therefore be used t o demonstrate the possible site of vitellogenin synthesis immunocytoch emically employing the peroxidase-anti-peroxidase (PAP) reaction. Hepa topancreas, sub-epidermal tissue, muscle, and ovary were fixed with pe riodate-lysine paraformaldehyde solution after which paraffin sections were made. In mature females, oocytes at the yolk globule stage, the hepatopancreas and the sub-epidermal tissue of the lateral somites sho wed positive PAP reactions. However, the sub-epidermal tissue of the v entral somites, follicular cells of the ovary and muscles did not. No positive reaction was observed in males and immature females. These re sults suggest that vitellogenin is synthesized in the hepatopancreas a nd at the sub-epidermal tissue in females at the exogenous vitellogene sis stage.