Annual cycle of morphological changes in the interrenal gland of the flounder Liopsetta pinnifasciata from the Amur Gulf (Peter the Great Bay of the Sea of Japan)

The annual cycle of morphological changes in the interrenal gland of the flounder Liopsetta pinnifasciata, a species which had been exposed over several decades to polluted waters of the Amur Gulf (Peter the Great bay of the Sea of Japan), is investigated. The curve of annual dynamics of the volume of nuclei of interrenal cells is U-form. The maximum size of nuclei is recorded in the period of perivitellogenous growth of oocytes and the minimum size is recorded at early stages of vitellogenesis. The area of epithelium of the interrenal gland in flounders is the lowest also in the beginning of the vitellogenous growth of oocytes. It is assumed that the uncommon annual cycles of changes in the interrenal gland of this flounder living in the Amur Gulf is an index of its stressed condition.