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Biomedical subjects

A Hervonen

Publications and source records attributed to A Hervonen.

At least 127 records · Page 7Linked to original sources
PubMed1978

The distribution and endocrine nature of the abdominal paraganglia of adult man.

The paraganglia of adult man were studied using the formaldehyde-induced fluorescence (FIF) method for histochemical characterization of biogenic monoamines. Microspectrofluorimetry was used to record the emission spectra and fluorescence intensities of the paraganglionic cells. The study of samples from six patients showed that well vascularized paraganglia were widely distributed throughout the retroperitoneal spaces. The paraganglia exhibited strong FIF with the spectral characteristics of monamines. Treatment with HC1 caused an increase in the fluorescence intensity of the paraganglia and a simultaneous shift of the emission maximum from 480--495 nm. This change suggests the presence of high concentrations of tryptophyl-containing peptides and is not due to monoamines. The possibility of a dual endocrine function for the paraganglia is discussed.

Abdomen↗
PubMed1978

Light and electron microscopic histochemistry of the monoamines in the human foetal sympathetic ganglion in culture.

Sympathetic ganglia of 13 to 19-week-old human foetuses were cultured in small pieces with and without nerve growth factor for up to 5 weeks in vitro. The cultures were studied using phase-contrast, fluorescence and electron microscopy. Monoamines were demonstrated with the formaldehyde-induced fluorescence method, with and without pretreatment of the cultures with catecholamines or monoamine oxidase inhibitor. In the long-term cultures, primitive sympathetic cells, sympathicoblasts of types I and II, and young sympathetic neurons showed a fine structure identical to that described earlier in vivo. There were virtually no satellite or Schwann cells in the cultures. The neurons showed a considerable capacity to grow new nerve fibres in culture, even without nerve growth factor. Nerve terminals with accumulations of synaptic vesicles were regularly observed, occasionally in synapse-like contact with other nervous structures. Large granular vesicles were regularly found in the sympathicoblasts after glutaraldehyde-osmium tetroxide fixation. After permanganate fixation, dense-cored vesicles typical of adrenergic neurons were not seen, either in the perikarya, or in the processes, although it was possible to demonstrate specific fluorescence. No small intensity fluorescent (SIF) cells were observed. Variable formaldehyde-induced fluorescence was observed in the nerve cell perikarya and nerve fibres. The intensity of the fluorescence increased after treatment of the cultures with monoamine oxidase inhibitor and after incubation with catecholamines.

Axons↗
PubMed1978

Effects of ageing on the histochemically demonstrable catecholamines and acetylcholinesterase of human sympathetic ganglia.

The sympathetic ganglia of adult and aged humans were obtained during vascular, gynaecological and urological surgery, and studied using the formaldehyde-induced fluorescence (FIF) method for histochemical demonstration of catecholamines. Microspectrofluorimetry was applied to characterize the emission spectra of the flurophores. The sympathetic ganglia contained two types of cells exhibiting FIF: the adrenergic neurons and the small, intensely fluorescent (SIF) cells. The adrenergic neurons contained pigment granules exhibiting autofluorescence with emission maximum at 530---540 nm. The number of these granules increased with age while the FIF of the neurons decreased. In the oldest patients, most of the neurons in the sympathetic ganglia showed only pigment fluorescence but not FIF. The decrease of the perikaryonal catecholamine stores is interpreted as a degenerative change leading to impaired function of the neurons. The patterns of AChE did not change with age. The SIF cells were sparse and were mostly observed near the ganglia, forming paraganglia of varying size. Because of the rarity of the SIF cells, the effect of ageing could not be judged reliably.

Acetylcholinesterase↗
PubMed1978

Paraganglia of the bladder.

Normal paraganglia containing high amounts of catecholamines are a constant feature of the wall of the bladder in elderly men. The paraganglia in this location might give rise to pheochromocytomas. The importance of the local endocrine effects in the regulation of the muscular tone in the bladder is discussed.

Chromaffin System↗
PubMed1978

Ultrastructure of synaptosomes from fetal rat brain.

The crude mitochondrial fraction P2 and subfractions of P2 were prepared from the brain stem, hemispheres and whole brain of 19-day-old fetal rats. Samples were fixed in glutaraldehyde-osmium, NaMnO4 or by Tranzer's triple fixation method (aldehydr-chromate-dichromate-osmium) and examined by electron microscopy. The C-fraction from whole brain was the main synaptosome fraction, containing 3.2% presynaptic terminals as counted from all membrane bound particles. The brain stem showed more presynaptic terminals than the hemisphere (2.8% versus 0.9%) suggesting a caudal-rostral maturation gradient for synaptogenesis. The maturity of the nerve endings obtained was very variable in contrast to the rather uniform synaptosomes derived from adult tissue. They varied from profiles without any substructures to mature synaptosomes displaying asymmetric synaptic junctions. Monoamine synaptosomes containing small granular vesicles were not detected in the present study, suggesting immaturity of the granular monoamine pool at this stage of development.

Animals↗
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↗
PubMed1976

Paraganglia in the urogential tract of man.

According to the earlier concept, the paraganglia of man are believed to degenerate during the first postnatal years after their dominance during the fetal period. Clinical case reports on persisting paraganglia led us to extensive exploration of surgical material obtained from urological and gynecological surgery. The formaldehyde induced fluorescence (FIF) was used for tracing the catecholamine containing tissues. The fluorescence intensities were recorded with a Leitz MPV 2 microspectrophotometer. Solitary, small paraganglia were found in all patients studied. They were especially frequent in the walls of the urinary bladder and in the connective tissue surrounding the urogenital organs. The intensity of the fluorescence was comparable to pharmacological standard of 10(-2) M noradrenaline and at the same level as the FIF of human fetal paraganglia. All cells of the paraganglionic clusters exhibited FIF and no signs of degeneration could be observed. It is suggested that the paraganglia of man do not degenerate postnatally but persist as a remarcable catecholamine reservoir, which might be of physiological importance.

Adult↗
PubMed1976

Ultrastructural identification of monoaminergic synaptosomes from one day old rat brain.

Synaptosomes from one day old and adult rat brain were studied. Specific cytochemical methods for demonstrating monoaminergic (MA) nerve endings were used. Permanganate fixation after preincubation with 5-OHDA or alpha-methyl-NA demonstrated MA synaptosomes. Their number was small in the adult (less than 1 %) and still smaller in the one day old rat brain. The MA synaptosomes from developing rats were different from the adult ones. The large amount of endoplasmic reticulum in developing synaptosomes suggests that granular vesicles are formed from endoplasmic reticulum in nerve endings.

Animals↗
PubMed1976

The paraganglia, a persisting endocrine system in man.

The paraganglia have been traced in surgical samples of para-aortic and pelvic retroperitoneal tissues using the formal-dehyde-induced fluorescence method for catecholamines. Clusters of catecholamine-storing cells were found in all (12) patients studied. Microspectrofluorometric recordings showed high amounts of catecholamine in the well-vascularized cell groups. A large proportion of the paraganglia, which are most prominent during the fetal period, also persist during postnatal life.

Adult↗
PubMed1975

Synaptosomes containing large agranular vesicles isolated from developing rat brain.

Using the subcellular fractionation technique the fine structure of the isolated nerve endings (synaptosomes) from the hemispheres and brain stem of the 1-day old and adult rat was examined. In the synaptosomal fractions of the brain of 1-day old rats we observed a new type of nerve endings containing predominantly large agranular vesicles about 1,000 A in diameter. After incubation with alpha-methylnoradrenaline or 5-hydroxydopamine these vesicles remained agranular. It is assumed that the new type of large vesicles represent developing synaptic vesicles.

Age Factors↗