MORPHOLOGICAL EVIDENCE FOR THE EXISTENCE OF 2 DISTINCT TYPES OF MITOCHONDRIA-RICH CELLS IN THE GILL OF THE CRAYFISH ASTACUS-LEPTODACTYLUS ESCHSCHOLTZ

An ultrastructural study was performed on gill epithelia of the crayfi sh Astacus leptodactylus. The filament and the lamina of the podobranc h were examined. In both structures a vascular system is lined by a sp ecialized epithelium covered by a cuticle. Different types of epitheli um were described in the gill filaments: either a thin epithelium with few organelles and probably involved in gas exchange or, in other fil aments, a thick epithelium with characteristics of a transporting epit helium (abundant mitochondria in close association with plasma membran e infoldings). The epithelium of the lamina is also of a transporting type but in this case the complex of membrane infoldings and mitochond ria is in an opposite orientation to that of the filament epithelium s uggesting a different role in osmoregulation. (C) 1997 Published by El sevier Science Ltd on behalf of The Royal Swedish Academy of Sciences.