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[Effect of etimizol on the ultrastructure of the dorsal hippocampus and autonomic ganglia of the rat heart].
The injection of aethimizol to rats (10 mg/kg) causes an irregular widening of cisternae of the granular endoplasmic reticulum in "light" pyramidal neurons of zone CA1 of dorsal hippocampus, which is considered as a depression of the neuronal apparatus of protein synthesis. A 1 mg/kg dose causes, in some synapses, a complex of changes supposed to express the activation of synapses. No essential changes were revealed in the heart neurons. Aethimizol acts selectively on the ultrastructure of central nervous system and does not exert a pronounced action on autonomic neurons.
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Subcellular compartmentation of prolactin in rat lactotrophs.
The intracellular localization of different molecular forms of prolactin was studied in various experimental models covering a wide range of secretory states. By correlating electron microscopy, morphometry and quantification of monomeric (small) and polymeric (big) prolactin after differential extraction procedures, big prolactin was found stored in secretory granules while small prolactin was loosely associated with all organelles involved in hormone synthesis and processing. No correlation with levels of lactotrophic secretory activity was detected by either the number of secretory granules or prolactin content in lactotrophs.
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The preoptic area of the domestic fowl. II. Ultrastructure of the medial preoptic area.
Numerous secretory parvocellular perikarya were found in the preoptic region of the domestic fowl (Gallus gallus). The dense-core secretory vesicles belong to two categories: vesicles with a diameter of (i)80-90 nm and (ii) 110-140 nm. Scattered magnocellular elements display larger dense-core granules. The parvocellular neurons form unit-like clusters, showing also zones of direct apposition of neuronal membranes. The surrounding neuropil is rich in synaptic structures, formed by at least three types of axon terminals, distinguishable on the basis of vesicular morphology. These observations confirm the findings in other avian species. The hypothetical function of this system of peptidergic neurons in the rostral hypothalamus of birds is discussed.
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Fine structure of the chromophobe in the pars distalis of the common snapping turtle, Chelydra serpentina.
Chromophobes of the pars distalis in young Chelydra serpentina have sparse cytoplasm with no specific granules; however, many cytoplasmic filaments are present. The chromophobes are connected to the other cell types by desmosomes, while different types of junctional specializations occur between adjacent chromophobes. Cytoplasmic filaments traverse the cytoplasm in a random manner and terminate on both the junctional complexes and the nuclear envelope. It is proposed that, in addition to providing a structural framework, the chromophobes may be involved in integrating cellular responses of the parenchyma to changes in the endocrine milieu.
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Ultracytochemistry of the synaptic ribbons in the rat pineal organ.
The synaptic complexes of the rat pinealocytes are neither cholinergic nor adrenergic. In the synaptic vesicles, a neurotransmitter carrier substance of lipid nature reacting with OsO4-Zn I2 mixture (similar to that present in both cholinergic and adrenergic vesicles) was not found. In addition, there were no indications of glucose-6-phosphatase or thiamine-pyrophosphatase activity in the synaptic vesicles. Thus, it appears that the synaptic vesicles do not originate from the rough or smooth endoplasmic reticulum. The synaptic ribbons do not contain carbohydrates, are of protein nature and possess some chemical resemblance to microtubules and microtubular bouquets. Appropriate ultracytochemical reactions have not shown detectable quantities of sodium and calcium ions in pinealocyte synaptic complexes.
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Ultrastructure of a regular arrangement of microtubules and neurofilaments.
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Structural changes of the pineals of blinded rats fed long term.
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A light and electron microscopic study of perineuronal glial cells and processes in the rabbit neccortex.
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Electron microscopy of the median eminence of the rat.
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Synaptic ribbon populations in the pineal gland of the rhesus monkey (Macaca mulatta).
Pinealocytes of rhesus monkeys that had been ovariectomized and given intramuscular injections of 250 micrograms estradiol-benzoate for 3 consecutive days tended to have more synaptic ribbons (SR) and exhibited a significantly greater size of ribbon fields (RF) compared to untreated animals. These data are consistent with hypotheses that pinealocyte function in primates is altered by hormonal imbalances and that the SR participates in this response. RF were positioned in various parts of the cytoplasm and along the plasma membrane. Participation of SR in direct cell-to-cell contacts was suggested by the formation of densities along the plasma membrane. It is postulated that large RF serve as storage organelles and that the formation of RF results from division of pre-existing SR in each field. Reconstructions made from serial thin sections revealed that profiles of RF comprised separate SR that were not folded and sectioned along various planes.