Changes in the apical surface of chloride cells following
acclimation of lampreys to seawater.
Bartels, Helmut, Andy Moldenhauer, and Ian C. Potter.
Abteilung f[umlaut]ur Zellbiologie und Elektronenmikroskopie,
Medizinische Hochschule Hannover, D-30625 Hannover, Germany; and
School of Environmental and Life Sciences, Murdoch University,
Murdoch, Western Australia 6150, Australia
APStracts 2:0210R, 1995.
Scanning electron microscopy (SEM) was used to study the changes that
occur in the morphological relationships between chloride and
pavement cells in the gills during acclimation of young adult
lampreys to seawater. Since chloride cells are located predominantly
between lamellae, and are thus obscured from view, the lamellae were
removed using a micromanipulator installed in a SEM. In gills of
animals maintained in river water, chloride cells could then be seen
to be disc-like and typically to form single rows between successive
lamellae. Following acclimation to seawater, the apical surfaces of
chloride cells lose their microvilli and change in shape from small
circles to rectangles that extend the full width between succesive
lamellae. These changes result in an increase in the length of the
paracellular pathway between chloride cells. Previous work has shown
that the number of strands of the zonulae occludentes sealing this
pathway declines under these conditions. This presumably leads to an
increase in paracellular permeability of the gill epithelium, thereby
providing the low resistance paracellular shunt required for the
passive movement of sodium into the environment during osmoregulation
in seawater. The above changes are reversed by transfer of lampreys
downwards to 10% seawater.
Received 14 February 1995; accepted in final form 19 July 1995.
APS Manuscript Number R111-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 July 1995.