FINE-STRUCTURE AND FUNCTION OF THE GUT EPITHELIUM OF PIKE EEL LARVAE

The development of the alimentary canal of pike eel, Muraenesox cinereus, that were hatched and reared in the laboratory, was examined. The larvae did not feed on zooplankton or phytoplankton and survived for 10 days. Histological and histochemical investigations showed that the alimentary canal was morphologically and functionally differentiated in 3 days after hatching and before exhaustion of the yolk. The foregut was not functional in absorption. The midgut absorptive cell was characterized by a well-developed lamellar membranous structure in the basal portion of the cytoplasm. Na+-K+ ATPase activity was demonstrated on the lamellar membrane of the structure. It suggests that water and solute transport is quite active in the midgut epithelium. Orally administered HRP (horseradish peroxidase) was ingested and intracellularly digested in the hindgut absorptive cells. Some of the HRP was transported, without complete digestion, into tissue spaces under the epithelium. Evidence suggests that pike eel larvae possibly utilize dissolved organic matter, including soluble macromolecules, as their nutrition sources. (C) 1995 The Fisheries Society of the British Isles