KHODABANDEH, Saber; CHARMANTIER, Guy; CHARMANTIER-DAURES, Mireille; Univ. of Tarbiat Modarres, Tehran, IRAN and UMII, Montpellier, FRANCE; Univ. of Montpellier II, FRANCE: From embryo to adult: ontogeny of the antennal glands in the lobster Homarus gammarus

Contrary to freshwater species, the ultrastrusture of the antennal glands in marine species is poorly documented. We investigate the build-up, fine structure and localization of Na/K- ATPase from the early embryos to the adult stage of Homarus gammarus. In adults, the gland is composed of a central coelomosac surrounded ventrally by a labyrinth divided in two (I and II), dorsally by a voluminous bladder. There is no nephridial tubule. Labyrinth and bladder cells presents cytological common features such as basal membrane infoldings associated with mitochondria, a cytoplasm rich in vacuoles, vesicles and swollen mitochondria, apical microvilli, cytoplasmic extrusions and the presence of Na/K- ATPase. In embryos, the undifferentiated cells of the future gland are detectable at EI 150 �m (EI = eye index, 640 �m at hatching). In embryos at EI 250 �m, an ectodermic tubular epithelium and a mesodermic coelomosac are differentiated. In later embryonic stages (EI 325-625 �m), the tubular epithelium lengthens to form an ectodermic sac. In larvae and at the first post-larval stage, the lumen of the ectodermic sac increases markedly, the epithelium of the ectodermic sac folds and progressively forms the labyrinth with three lobes surrounding the coelomosac. The end part of the ectodermic sac forms the bladder and duct. The presence of Na/K- ATPase was detected at EI 425 �m at the basal side of the ectodermic sac cells; in later embryos and in larvae, the immunofluorescence was intense. A weak fluorescence was detected in the labyrinth and bladder of post-larvae. Thus the antennal glands of the lobster possess active ion exchange capabilities starting in late embryos, based on the presence of ionocytes in the labyrinth and the bladder.