OSMOREGULATORY-LIKE MITOCHONDRIA-RICH CELLS IN THE DEVELOPING PANCREATIC DUCTS OF YOUNG ANURAN TADPOLES

Pancreatic ducts of young posthatching Rana temporaria tadpoles are th e main component of the developing pancreas. At this stage (free-swimm ing tadpoles with internal gills), duct cells display a high degree of development of basal and lateral outfoldings of the cell membrane wit h extensive interdigitation, and numerous mitochondria are present thr oughout the cytoplasm. Wide intercellular spaces also exist, sometimes forming canaliculi-like structures. Since these traits are characteri stic of cells engaged in osmotic regulation, we suggest the possibilit y that this temporary duct system participates in such control. Duct c ells in tadpoles with well-developed hindlegs have diminished interdig itation, and mitochondria are localized apically.