Morphological Evidence for the Existence of Two Distinct Types of Mitochondria Rich Cells in the Gill of the Crayfish Astacus leptodactylusEschscholtz

An ultrastructural study was performed on gill epithelia of the crayfish Astacus leptodactylus . The filament and the lamina of the podobranch were examined. In both structures a vascular system is lined by a specialized epithelium covered by a cuticle. Different types of epithelium were described in the gill filaments: either a thin epithelium with few organelles and probably involved in gas exchange or, in other filaments, a thick epithelium with characteristics of a transporting epithelium (abundant mitochondria in close association with plasma membrane infoldings). The epithelium of the lamina is also of a transporting type but in this case the complex of membrane infoldings and mitochondria is in an opposite orientation to that of the filament epithelium suggesting a different role in osmoregulation.