ON THE KIDNEY AND THE ADRENOCORTICAL TISSUE OF TOOTHED SMELT, OSMERUS MORDAX DENTEX AND SURF SMELT, HYPOMESUS PRETIOSUS JAPONICUS AND THEIR COLD ADAPTATION (Twelfth Symposium on Polar Biology)

摘要

The kindneys and the adrenocortical tissues of toothed smelt, Osmerus mordax dentex and surf smelt, Hypornesus pretiosus japonicus were investigated by light microscopy. Their kidneys, which are glomerular, show no changes in the Bowmanu27s capsules and glomeruli between the fishes caught in summer and those in winter. In contrast, the saffron cod, Eleginus gradlis previously observed, showed seasonal difference of the glomerulus which is considered related to the conservation of antifreeze serum glycoprotein. The present results suggest that toothed smelt and surf smelt possess a different adaptive mechanism for cold water from that of the saffron cod. The adrenocortical tissue is located around the posterior cardinal veins in the head kidney. No seasonal difference in the cross-sectional areas of the nuclei of adrenocortical cells was observed in either the toothed smelt or the surf smelt. It is concluded that the adrenocortical cells are probably not related directly to cold adaptation in these fishes.