Thyroxine distribution in the hemolymph, hepatopancreas, ovary, sponge, and larvae of female mud crabs (Scylla serrata) during ovarian maturation

Abstract

An experiment was conducted to study the profiles and the dynamics of thyroxine in the hemolymph, hepatopancreas, ovary, sponge, and larvae of female mud crabs during ovarian maturation. The experiment consisted of three parts. First, we measured thyroxine concentrations in the hemolymph, hepatopancreas, and ovary. Second, we measured cholesterol, neutral lipid, phospholipid, and protein in the ovary. Third, we determined thyroxine concentrations in the sponge and larvae. During vitellogenesis, the highest thyroxine concentration was found in the hepatopancreas, followed by the hemolymph and ovary. Thyroxine concentrations in the hemolymph and the ovary increased with the increased stage of vitellogenesis. However, thyroxine concentrations in the hepatopancreas decreased with the increased stage of vitellogenesis. Cholesterol and phospholipid concentrations in the ovary increased from vitellogenic stage 1 to stage 2, but began to decline in vitellogenic stage 3. In contrast, neutral lipid concentrations decreased from vitellogenic stage 1 to stage 2, while the concentration of protein in the ovary increased with the advanced of vitellogenic stage. Concentration of thyroxine in the sponges was the highest during the early embryonal stage and continued to decrease with the completion of yolk absorption and during the transformation to the juvenile stage. The results imply that thyroxine plays a critical role in ovarian maturation and embryonic development of mud crabs.