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Identification and morphometric evaluation of the synapses of optic nerve afferents in the optic tectum of the axolotl (Ambystoma mexicanum).
Ther terminals of retinal afferents in the tectum of the axolotl have been identified ultrastructurally using techniques of horseradish peroxidase-filling and degeneration. The mitochondria in filled structures show a characteristic electron-lucent matrix. After both eyes have been removed, terminals with light mitochondria disappear from the area known to receive an optic input. In this area the presence of light mitochondria is almost always diagnostic of the retinal origin of a bouton. The synapses are similar to those assumed to be of retinal origin in other vertebrates. Detailed morphometric analysis has been carried out on identified optic synapses in the optic tectum of the axolotl.
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[Electron-microscopic investigations on the localisation of the thiamine pyrophosphatase in the hippocampus of the Wistar rat (author's transl)].
This report describes the ultratopochemical localization of the thiamine pyrophosphatase in the pyramidal cells of the CA3 region of Wistar rat hippocampus. Attention was focussed on the occurrence of the enzyme out of the Golgi field. Thiamine pyrophosphatase was demonstrated in dendrites and - to a lesser extent - in axons. TTPase containing synapses were rather seldom and belonged to the axo-dendritic type. A hypothetic model concerning the transport and the distribution of the enzyme within the cell is presented.
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Ultrastructural features of pituicytes in the neural lobe of adult rats. The cytoplasm.
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The pineal gland of intact, hypophysectomized, or ovariectomized rats. Light and electron microscopic studies.
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[Growth and transformation of the embryonal ependyma in tissue culture].
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[Multivesicular bodies of the neurosecretory cells of the supraoptic nucleus of the rat].
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Myeloid bodies associated with lipid droplets in pinealocytes of blind, blind-bulbectomized, blind-underfed or blind cold-exposed rats.
The ultrastructure of pinealocytes was studied in rats subjected to manipulations known as enhancers of pineal actions: blindness (B), blindness + olfactory bulbectomy (BObx), blindness + underfeeding (BU), blindness + cold exposure (BC). A large number of myeloid bodies (MBs) were found especially in the light pinealocytes of BObx, BU and BC rats but not in intact controls. These MBs were, in most cases, associated with lipid droplets. The presence of a large number of MBs in rats in which pineal-dependent gonadal impairment has been demonstrated, strongly supports the hypothesis that MBs play a role in pineal photoneuroendocrine activity.
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Ultrastructural changes in neurons of the anterior subdivision of the rat hypothalamic ventromedial nucleus following repeated immobilization stress.
The fine structure of neuronal somata of the anterior subdivision of the hypothalamic ventromedial nucleus (VMN) was studied in repeatedly immobilized rats. After the 40th immobilization daily for 150 min a small population of neuronal somata containing endoplasmic reticulum formations classified as lamellar bodies and whorls were identified in the area investigated. These neuronal somata differed from the neighbouring perikarya of VMN also in several other ultrastructural features. They showed an extraordinarily dilated cisternae of the rough endoplasmic reticulum and of the Golgi complexes, moderately swollen mitochondria and a large number of free ribosomes evenly distributed in the cytoplasm.
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Ultrastructural effects of perfomic acid oxidation of epoxy-embedded tissue with and without early uranyl staining.
Epoxy-embedded blocks of glutaradehyde and OSO4 fixed adenohypophyseal tissue were immersed in performic acid, rinsed and sectioned for electron microscopy. Sections exhibited a general image intensity equivalent to control sections but their stainability with both uranyl acetate and lead citrate stains was increased. It was concluded that osmium was not removed by performic acid oxidation. Membranes of endoplasmic reticulum and the Golgi apparatus were not visible, and other components (acidophil granules, in particular) were markedly distored in shape after oxidation. Such changes, however, were not evident in specimens previously exposed to uranyl acetate during ethanol dehydration.
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A centrosomal inclusion (striped nebulous body) in pinealocytes of the golden hamster.
Electron microscopy has revealed the presence of a special cytoplasmic body in the centrosomal area of pinealocytes of the golden hamster, Mesocricetus auratus. It consists of branching electron-dense ribbons embedded in a flocculent matrix of moderate electron density, and is tentatively named the 'striped nebulous body' (SNB). The dense ribbon usually appears as a thick band accompanied by a parallel thin one to one side. The SNB is not bounded by a membrane, and is roughly round or kidney-shaped. Closely associated with the SNB are centrioles, microtubular sheaves and striated fibrils, the latter two being centriolar derivatives. The observations suggest that the SNB might be formed by the amalgamation of these microtubular sheaves and striated fibrils. In golden hamsters, pinealocytes often have multiple centrioles and centriolar derivatives. The SNB of adult hamsters is seen in the pinealocytes of both sexes, irrespective of the season of the year and the activity of the pineal gland. The functional significance of this body remains to be studied.