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Biomedical subjects

L Rechardt

Publications and source records attributed to L Rechardt.

At least 73 records · Page 4Linked to original sources
PubMed1978

Age-dependent increase in the non-specific cholinesterase activity of the capillaries in the rat neostriatum.

Histochemically demonstrable non-specific cholinesterase activity in the capillaries of the neostriatum of 3-5-month-old rats was much weaker than that of 24-27-month-old rats. In the young adult rats the activity was electron microscopically localized mainly in endoplasmic reticulum and perinuclear cisternae of the endothelial cells, while capillaries of old rats showed a positive reaction also in the basal lamina and outer cell membranes of glial processes.

Aging↗
PubMed1977

Permanganate fixation demonstrates the monoamine-containing granular vesicles in the SIF cells but not in the adrenal medulla or mast cells.

Three types of monoamine-storing cells were fixed with permanganates and analyzed ultrastructurally. The SIF cells contained the typical granulated vesicles characteristic of monoamines. On the other hand, both the catecholamine-storing cells in the adrenal medulla and the mast cells were devoid of a dense core in their monoamine vesicles. This is surprising, since permanganate is considered a reliable means of demonstrating monoamines at the fine structural level. The significance of this finding is discussed against the close relationship between SIF cells and cells of the adrenal medulla. Because permanganate as a fixative is widely used in monoamine fine structural cytochemistry, the present findings undoubtedly need further clarification.

Adrenal Medulla↗
PubMed1977

Electron microscopical demonstration of adenylate cyclase activity in nervous tissue.

Adenylate cyclase (EC4.6.1.1) activity stimulated by norepinephrine and dopamine was demonstrated histochemically by electron microscopy in the cerebral cortex and caudate nucleus of the rat. The precipitating agent in the histochemical reaction was cobalt, which was shown biochemically to increase the adenylate cyclase activity. The reaction product was located in the synapses, being contiguous attached to the postsynaptic membrane. It was also located in the plasma membrane of some nerve fibers. Alloxan, the specific inhibitor of adenylate cyclase, inhibited the reaction in the cerebral cortex and caudate nucleus, and haloperidol had a somewhat similar effect in the caudate region.

Adenylyl Cyclases↗
PubMed1977

Simultaneous demonstration of cholinesterases and glyoxylic acid-induced fluorescence of catecholamines in stretch preparations.

A combined simultaneous method to demonstrate adrenergic nerves using glyoxylic acid-induced fluorescence and nerves showing cholinesterase activity using the thiocholine technique is described in whole-mount preparations. The subcutaneous fascia and the right atrium of the heart of the rat and guinea-pig were used as tissue specimens, and the innervation patterns of adrenergic and cholinergic nerves were demonstrated in UV and transmitted light. Technical points and the limitations of the method are discussed.

Animals↗
PubMed1977

Ultrastructural neurohistochemical evidence for a neuro-endocrine link in the regulation of the extra-hepatic biliary dynamics.

Electron microscopical neurohistochemical studies of the choledocho-duodenal junction of the cat revealed acetylcholinesterase-positve nerve terminals closely abutting on ("ectopic"), mono-amine(s)-containing alpha-cells (of the islets of Langerhans) scattered in small clusters between bundles of the sphincteric smooth muscle (of Oddi). The cell membrane of the alpha-cells at and near the site of the neuro-effector contacts was reactive, too. This finding may be considered as some evidence for cholinergic innervation of cholinoceptive neuro-endocrine cells, and obviously represents one of the neuro-endocrine links involved in the regulation of the extra-hepatic biliary dynamics, demonstrated earlier in physiological and pharmacological studies.

Acetylcholinesterase↗
PubMed1976

Electron microscopic localization of adenylate cyclase activity of white and brown adipose tissue of the rat and chicken.

Brown adipose tissue of newborn rats and chicken embryos and white adipose tissue of adult rats were studied. Adenylate cyclase (EC 4.6.1.1.) activity stimulated by 0.1 mmol/l noradrenaline was demonstrated using an electron microscopic histochemical method. The reaction product was visualized as a cobalt salt in the plasmalemma of the adipocytes. The adipocytes of the brown adipose tissue of the newborn rats showed most intense reaction in the outer surfaces of their plasmalemma. Alloxan totally inhibited the enzymatic reaction. The histochemical reaction used in the present study probably demonstrated the hormonal receptor sites in the plasmalemmas of the adipocytes which are stimulated by noradrenaline.

Adenylyl Cyclases↗
PubMed1976

Histochemical localization of adenylate cyclase in cultured sympathetic neurons.

The catecholamine-stimulated adenylated cyclase activity was histochemically demonstrated at ultrastructural level in the cultured neurons of the sympathetic ganglia of the chick embryo. Adenylate cyclase activity was demonstrated in the axolemma of the axons and axon terminals, however not inside the axons. Heavy precipitates of the enzymatic reaction product was observed intracellularly in some cell processes identified as dendrites of the sympathetic neurons. In contrast to the extensive reaction in the neuropil, the reaction for the catecholamine-stimulated adenylate cyclase was scarse in the perikarya of the neurons. Only occasional spots of adenylate cyclase activity could be demonstrated in the plasmalemma of some neurons, and no reaction product was observed in the cytoplasm. No difference in the localization of the adenylate cyclase activity was observed when either dopamine or noradrenaline were used for stimulation. The possible roles of the catecholamine-stimulated adenylate cyclase in the function of the interneuronal connections between the aminergic neurons of the sympathetic ganglion are discussed.

Adenylyl Cyclases↗
PubMed1976

Lamellated bodies in the neurons of the submucosal ganglia in the sphincter of Oddi of the dog.

Peculiar neurons and nerve processes, which contained remarkable amounts of lamellated, electron-dense bodies, "myeloid bodies", are described. They were found among normal looking neurons in the submucosal ganglia of the sphincteric musculature of Oddi. The innervation and ultrastructure of the ganglia were studied in apparently healthy, young dogs bred for experimental purposes. The possible function of these neurons and processes is discussed.

Ampulla of Vater↗
PubMed1976

Observations on the functional cytochemistry of pars intermedia of the rat hypophysis.

Light and electron microscopic histochemical reactions were studied in the cells of pars intermedia of the rat. The possible correlations between enzymatic reactions and endocrine functions of these cells were discussed. By combined formaldehyde and chloral vapour treatment the cells of the pars intermedia exhibited a strong yellow fluorescence suggesting the presence of a peptide or peptides with NH2-terminal tryptophan. Masked metachromasia after acid hydrolysis was probably due to these peptides. Only a weak or no alpha-glycerophosphate dehydrogenase and nonspecific esterase activity was observed in the cells of pars intermedia compared to the cells of pars distalis suggesting low production rate of hormone synthesis. Specific and non-specific cholinesterases were demonstrated light and electron microscopically constantly in the cells bordering the lobules. These cells probably represent a certain type of glial cells. In the other cells the enzymatic activities varied markedly in intensity and distribution showing different ultrastructural localizations. Thus cholinesterase activities in the cells of pars intermedia reflect possibly different functional stages of the cells in their hormone production, storage and secretion processes.

Acetylcholinesterase↗
PubMed1976

Innervation of human axillary sweat glands. Histochemical and electron microscopic study of hyperhidrotic and normal subjects.

Adrenergic nerves were demonstrated by formaldehyde-induced fluorescence and cholinergic nerves using thiocholine techniques to demonstrate acetylcholinesterase activities at the light and electron microscopic levels. The specimens were taken during surgery from the axillae of hyperhidrotic patients and normal voluntary controls. No fluorescent nerves were found around eccrine or apocrine sweat glands in hyperhidrotic or normally sweating axillae. Both eccrine and apocrine sweat glands exhibited a nerve network showing acetylcholinesterase activity. There was no marked difference in the innervation patterns or in the intensity of the acetylcholinesterase reaction of the nerves in the hyperhidrotic patients or normal subjects. Ultrastructurally the acetylcholinesterase-positive nerves were seen in the vicinity of both eccrine and apocrine glands, but these nerves were outside the basement membrane.

Axilla↗
PubMed1975

Electron microscopic observations on the innervation of the sphincter of Oddi in the dog.

The ultrastructure and acetylcholinesterase activity of the intrinsic innervation of the sphincter of Oddi of eight adult dogs was studied by electron microscopy. A rich distribution of unmyelinated axons embedded individually or as groups within Schwann cell cytoplasm ("innervation fasciculee"), is to be observed. A few myelinated fibres were also observed. Many of the axons are acetylcholinesterase-positive. Three main types of nerve terminals are distinguished according to their vesicle populations. Individual nerve cells or small groups of nerve cells were scattered between the smooth muscle bundles and in the lamina glandularis mucosae. The cytoplasm of some neurons contains many electron dense spherical bodies resembling "myeloid bodies", and many lysosomes. Nerve terminals synapse onto both neuronal perikarya and their dendrites. Within the nerve fascicles, close appositions between the terminals occur frequently probably representing the most peripheral inter-neuronal integrative link in the neural regulation of the function of the sphincter of Oddi. -- The gap between nerve terminals and smooth muscle cells usually measures several thousands of A. Closer appositions are seldom seen, and no synaptic complexes can be observed.

Acetylcholinesterase↗