THE HYPOBRANCHIAL GLAND OF SOME PROSOBRANCHIA (MOLLUSCA GASTROPODA) LIVING IN DIFFERENT HABITATS: A COMPARATIVE HISTOCHEMICAL STUDY

SUMMARY The present paper provides a comparative histochemical study of the hypobranchial gland of some Prosobranchs (Mollusca Gastropoda) living in different habitats. The three species studied were Murex brandaris L. (a marine species), Viviparus viviparus L. (a freshwater species) and Pomatias elegans Muller (a terrestrial species). A noticeable thickened hypobranchial gland is present in the mantle of Murex brandaris, while in the other two species the gland is reduced. In Viviparus viviparus and Pomatias elegans there is an extremely simple gland in the mantle without purpurigen cells. The gland structure does not change during the seasons of the year in Murex and in Viviparus: on the contrary, in Pomatias the development of this gland is quite different in autumn and in spring. This fact, in our opinion, may be related to the terrestrial habitat of this species.