Steroid hormone in marine bivalve molluscs of the annual cycle

This article describes the features of quantitative distribution of glucocorticoid steroid hormones — hydrocortisone and corticosterone – at different stages of the life cycle of the Mediterranean mussel (Mytilus galloprovincialis) and the European flat oyster (Ostrea eduliss). The author identifies a common pattern of hormone dynamics consisting in a reduction in the level of hormones in molluscs in the course of maturation. Interspecies differences in the ratio of hormone levels are described. It is suggested that glucocorticoids participate in the regulation of gametogenesis of the investigated species.