Morphofunctional changes of the interrenal gland and of ultrastructure of chloride cells in intact and hypophysectomized juveniles of starred sturgeon <Emphasis Type="Italic">Acipenser stellatus</Emphasis> (Acipenseridae) in the course of adaptation to sea water |
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Authors: | L S Krayushkina O G Semenova |
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Institution: | 1.Department of Ichthyology and Hydrobiology,St. Petersburg State University,St. Petersburg,Russia;2.Pavlov Institute of Physiology,Russian Academy of Sciences,St. Petersburg,Russia |
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Abstract: | The impact of hypophysectomy on the state of the interrenal gland and ultrastructure of chloride cells of gills is investigated
in 18-month old juveniles of starred sturgeon Acipenser stellatus in the process of its adaptation to artificial sea water (14.6‰). Hypophysectomized juveniles, similarly to intact juveniles,
are able to support a relative stability of osmolarity of blood serum in the course of adaptation to sea water by transition
from hyperosmotic to hypoosmotic type of osmoregulation. Changes in the investigated parameters of cells of the interrenal
gland (volume of nuclei, areas of cells and of lipophilic vacuoles) occurring in the hypophysectomized and in intact specimens
in the process of adaptation to sea water are generally similar, but have different dynamics. In contrast to many teleostean
species, in acipenserids the hypophyectomy does not cause atrophy of the interrenal gland. The latter is incorporated in the
process of regulation in the course of adaptation of fish to sea water. Hypophyecotmy results in partial destruction of organoids
in some chloride cells of gills. However, when the fish are transferred to sea water, the structural changes occur in chloride
cells characteristic of their transition to the excretory state. This may happen only at activation of the transport enzyme
Na+/K+-ATPase of these cells by cortisol produced by the interrenal gland. In the absence of hypophysis, the functional connection
of organs of the axis hypothalamus (ACTH-immunopositive cells of tuberal nucleus) → the interrenal gland → chloride cells
is realized in the fish. |
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