Specific Cell Membrane Differentiation in the Tanycytes and Glial Cells of the Organum Vasculosum of the Lamina Terminalis in Dog

In the medial habenular nucleus of the rat, ependymal and endothelial membrane specializations were studied with TEM and freeze-fracturing. They comprise ependymal adherent junctions - not manifest in freeze-fracture replicas-, gap junctions, and membrane-associated orthogonal particle complexes ("assemblies") - not identifiable in thin-sectioned material. Ependymal tight junctions being absent, no brain-liquor barrier exists. The capillary endothelium is provided with tight junctions only. Intraventricularly injected HRP was transported in large amounts through the ependyma, mainly through the intercellular spaces and additionally by way of massive pinocytosis through the cytoplasm of particular ependymal cells only, and finally through the parenchymal intercellular compartments towards habenular capillaries. Following intravenous injection of HRP, considerable transport of the enzyme took place by means of transendothelial pinocytosis, followed by some pinocytotic transport through diverse parenchymal elements and markedly profuse incorporation and lysis within pericytes. The habenular blood-brain barrier appeared to be considerably leaky with respect to HRP.

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Membrane specializations and their relation to HRP transport in the medial habenular nucleus of the rat

Cupedo

Deweerd

Dijk

1985

Anat Embryol

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Distribution patterns of orthogonal arrays and alkaline phosphatase in plasma membranes of satellite cells in rat spinal ganglia

1985

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The plasmalemmal structure of satellite cells in the lumbar spinal ganglia of rat was examined by freeze-fracture and by a cytochemical method for the demonstration of alkaline phosphatase activity. Plasma membranes of satellite cells are the only ones in the ganglia to contain, in addition to globular intramembrane particles, orthogonal arrays of particles 6-7 nm in diameter. The arrays are most concentrated in the portions of the membranes contacting the basal lamina, or outer membranes; they decrease considerably in number in lateral membranes, and are rare in the membrane regions adjacent to the neuronal perikaryon, or inner membranes. Such gradual decrease in array density in satellite cells suggests regional differences of plasma membrane properties within the same cell. Alkaline phosphatase, which was chosen as a cytochemical marker for membrane activity because of its relation to transport function, localizes to inner and lateral membranes, and not to outer membranes of satellite cells. The absence of correlation between localization of orthogonal arrays and such enzymatic activity suggests that the membranes provided with many arrays possess some characteristics different from other membranes that may exclude transport activity. The possible significance of orthogonal arrays and their close association with the basal lamina are discussed.

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Freeze-fracture analysis of plasma membranes of isolated astrocytes from rat brain

1983

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Specific Cell Membrane Differentiation in the Tanycytes and Glial Cells of the Organum Vasculosum of the Lamina Terminalis in Dog

Cited by 4 publications

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Membrane specializations and their relation to HRP transport in the medial habenular nucleus of the rat

Membrane specializations and their relation to HRP transport in the medial habenular nucleus of the rat

Distribution patterns of orthogonal arrays and alkaline phosphatase in plasma membranes of satellite cells in rat spinal ganglia

Freeze-fracture analysis of plasma membranes of isolated astrocytes from rat brain

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