title: Fine structure of the interplatelet area in the gills of the macrophthalmia stage of the river lamprey, Lampetra fluviatilis (L.).
abstract: The interplatelet epithelium of the gills of freshwater and seawater adapted macrophthalmia stages of the river lamprey, Lampetra fluviatilis, was studied by electron microscopy. Three main cell types: basal, ion-excretory and superficial cells were identified and described. Ion-excretory cells were exposed to the environment in sea water but covered by a layer of superficial cells in fresh water. Electron-dense secretory granules in the apex of the cell were more abundant in fresh water. In fresh water, a few of the superficial cells contained numerous mitochondria and were identified as ion-uptake cells. In view of the scarcity of ion-uptake cells, the possibility that the ion-excretory cells are also responsible for ion-uptake in fresh water is discussed. Phagocytic removal of degenerating ion-excretory cells may be an important mechanism for the conservation of materials in a starving animal.
mesh_terms: D000818:Animals; D005399:Fishes / Q000254:growth & development*; D005618:Fresh Water; D005880:Gills / Q000648:ultrastructure*; D007798:Lampreys / Q000254:growth & development*; D012623:Seawater; D014882:Water-Electrolyte Balance