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T Schuster

Publications and source records attributed to T Schuster.

At least 109 records · Page 6Linked to original sources
PubMed1982

[Quantitative morphologic examination of the vesicle population of mixed synapses--method and significance].

Quantitative electron microscopic investigations have been performed regarding the population of clear round vesicles within the axosomatic mixed contacts between secondary vestibular and oculomotor neurons of the trout. The measurements are based on a subdivision of the axon terminal area into single fields which topographically belong to different synaptic types (active zone, gap junction) of this mixed contact. Furthermore, areas between active zones and gap junctions ("intermediate zones") and areas along the lateral membranes of the axon terminal ("border zones") have been analyzed. The following vesicle parameters have been estimated stereologically: volume density (Vvv), surface density (Svv), numerical vesicle density (Nvv) mean vesicle volume (Vv) and mean vesicle surface (Sv). In this connection, aspects of the homogeneous distribution, of number and size of the organelles hae been investigated. The results obtained show a characteristic distribution in number and size of vesicles inthe presynaptic areas of the different membrane specializations of this mixed synapses. The results further indicate that two different pools of clear round vesicles exist in this mixed synapse, clear synaptic vesicles for chemical transmission and gap junction vesicles. In relation to the synaptic vesicles, a recycling mechanism is suggested. Gap-junction vesicles may function as Ca++ transport organelles to regulate gap junction permeability. A possible role in trophic tasks of the gap junction is also discussed.

Animals↗
PubMed1981

[Evidence of the recycling of vesicle membranes by means of morphometric measurement of the vesicle density (author's transl)].

Quantitative-electron microscopic investigations have been performed on large morphologically mixed synapses in the oculomotor nucleus of the trout with the aim to get some hints at recycling processes of vesicle membranes. For this reason vesicle density of the presynaptic area and number of vesicle attachment sites of the presynaptic membrane of the active zones within these mixed contacts have been estimated in two different experimental groups. Furthermore, vesicle density near the unmyelinated axolemma of the axon terminal has been measured in both groups. The results obtained support the view that a recycling of vesicle membranes occurs in morphologically mixed synapses, probably also over the axolemma of the so-called extended extracellular spaces, which are interrupting the contact area between the two neuronal elements. The question of a recycling of gap-junction-vesicles has not been answered.

Animals↗
PubMed1981

[Asymmetrical gap junctions in the fish brain (author's transl)].

Morphologically asymmetrical or symmetrical gap junctions are to be distinguished from each other by two features, first, by the distribution of amorphous electron dense cytoplasmic material and, second, by the presence or absence of vesicles. Morphologically asymmetrical gap junctions are therefore characterized by the presence of submembranous material only on one side of the contact. The distribution of this material along the synaptic membrane reveals different forms. In vertebrates, vesicles if present occur only on the opposite side of the junction. Comparing morphologically symmetrical and asymmetrical gap junctions with electrophysiologically rectifying or non-rectifying synapses it has to be stated that a correlation is not possible at this time. In a topografic sense it can be noted that dendrodentritic electric synapses are always symmetrically built, whereas axosomatic and axodendritic junctions are often asymmetrically formed.

Animals↗
PubMed1978

[Reaction kinetic studies on the formation of n-nitrosoephedrine in vitro and in vivo (author's transl)].

N-Nitrosoephedrine was synthesized at a high yield (greater than 90%). The influence of pH on the reaction process (ephedrine sulfate + nitrous acid in hydrochloric acid) was investigated and the pH-optimum determined. Furthermore the influence of coffee, ascorbic acid, citric acid, cyclamate/saccharin (10:1), smoke condensate of cigarettes, glucose and ethanol on the reaction process was also determined. The tests with animals (rats) showed that N-nitrosoephedrine could be detected in serum after the oral application of ephedrine sulfate and sodium nitrite.

Animals↗
PubMed1978

Ultrastructure of astroglial contacts in rat cerebellar cortex.

Interfaces of the astroglial Bergmann fibres in the rat cerebellar cortex were investigated under the electron microscope. The straight interfaces revealed numerous contacts of a special junctional type having a mean length of 0.9 micro m. A substantial area of the Bergmann fiber surfaces was found to be connected with these junctions. Electron-dense material forming knoblike particles were observed attached with a certain regularity to the inner surfaces of both junctional membranes.

Animals↗
PubMed1977

[Enzyme histochemical investigations of the nucleus nervi oculomotorii of Salmo irideus (Gibbons 1855) during biomorphosis. I. Transmitter enzymes].

1. The activities of the transmitter enzymes acetylcholine esterase (AChE), monoamine oxidase (MAO) and gamma-aminobutyrate transaminase (GABA-TR) were investigated in the nucleus nervi oculomotorii of Salmo irideus (Teleostei) during biomorphosis. 2. AChE as well as MAO-activity could be demonstrated already before the time of hatching, whereas GABA-TR occured from the 10th day post hatching. 3. In earliest stages the AChE activity was found in the neuronal pericarya of the nucleus n. III, but later on a strong increase occured in vestibular presynaptic terminals establishing synaptic contacts with the lateral surface of the large pericarya, especially in the medial part of the dorsal subnucleus and the ventral subnucleus. In adults the enzyme activity was localized in vestibular nerve fiber terminals exclusively due to the loss of enzyme activity in the pericarya. 4. The activity of MAO was found surrounding the neurons of the nucleus nervi oculomotorii with stronger deposits of reaction product at the medial surface that is not occupied by cholinergic terminals. 5. Besides non reacting neurons in all parts of the nucleus some cells in the transition zone between the medial and lateral area of the dorsal subnucleus, exhibited high cytoplasmatic GABA-TR activity. 6. The different ways of chemical transmission between nerve terminals and the neurons of the nucleus nervi oculomotorii are discussed.

4-Aminobutyrate Transaminase↗
PubMed1975

[Electron microscopic identification of spoon-like contacts in the oculomotor nerve of the trout].

In the nc. n. oculomotorii of the trout exist different types of axonal terminals of second order vestibular neurons. In semithin sections there are observed seldom very large end-knobs (calyciferous endings). Electron microscopic pictures of the same terminal show typical spoon-like endings. A random sample like analysis of the mitochondrial density refers to functional differences between the different types of endings. A intramitochondrial cristaline inclusion in the axoplasma of a neuron is shown.

Animals↗