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

The development of the alimentary canal of pike eel, Muraenesox cinere us, that were hatched and reared in the laboratory, was examined. The larvae did not feed on zooplankton or phytoplankton and survived for 1 0 days. Histological and histochemical investigations showed that the alimentary canal was morphologically and functionally differentiated i n 3 days after hatching and before exhaustion of the yolk. The foregut was not functional in absorption. The midgut absorptive cell was char acterized by a well-developed lamellar membranous structure in the bas al portion of the cytoplasm. Na+-K+ ATPase activity was demonstrated o n the lamellar membrane of the structure. It suggests that water and s olute transport is quite active in the midgut epithelium. Orally admin istered HRP (horseradish peroxidase) was ingested and intracellularly digested in the hindgut absorptive cells. Some of the HRP was transpor ted, without complete digestion, into tissue spaces under the epitheli um. Evidence suggests that pike eel larvae possibly utilize dissolved organic matter, including soluble macromolecules, as their nutrition s ources. (C) 1995 The Fisheries Society of the British Isles