Morphological aspects of chromaffin tissue: the differential fixation of adrenaline and noradrenaline.

The morphological aspects of chromaffin tissue are reviewed, based mainly on our studies on the mouse adrenal gland. Particular attention was focused on the differential fixation of adrenaline and noradrenaline, and on the uptake and storage of [3H]dopa, [3H]dopamine and related substances in the adrenaline-storing (A) and noradrenaline-storing (NA) cells. Scanning electron microscopy combined with the NaOH-maceration method was useful for demonstrating the 3-dimensional organisation of nerve terminals, chromaffin cells, glial elements and vascular elements. In transmission electron microscopy, 3 types of chromaffin cell were distinguished. They were A, NA and SGC (small granule chromaffin) cells. After glutaraldehyde fixation followed by postosmication, A cell granules showed lower electron density, whereas NA cell granules were solid and dark. This difference in appearance between A and NA cells was first explained by the hypothesis that, after glutaraldehyde fixation, most of the adrenaline dissolved, whereas noradrenaline was precipitated in situ. Later, this hypothesis was supported by a series of autoradiographic and radioisotopic assay studies using [3H]dopa, [3H]dopamine and related substances; when [3H]adrenaline occurred, radioactivity in A cells mostly disappeared in the specimen, whereas that in the NA cells remained. At 15-60 min after an i.p. injection of [3H]dopa or [3H]dopamine, the concentration of radioactivity in A cells was higher than that in NA cells. However, in hypophysectomised mice, the radioactivity was low and evenly distributed in these 2 types of chromaffin cell. It was deduced that the carrier activities for extracellular dopa and dopamine were made greater in the A cells than in the NA cells by the pituitary gland. The hypophysectomy effects were restored by i.p. administration of ACTH.

Comparative morphology, cytochemistry and innervation of chromaffin tissue in vertebrates.

Chromaffin cells were observed singly or in clusters in the heart and sympathetic cord of 2 genera of dipnoan fish, Protopterus and Lepidosiren. They were invariably found in close association with the autonomic sympathetic nervous system and at sites where chromaffin cells or their precursors are situated in mammals during ontogenetic development. X-ray microanalysis demonstrated that they contained a primary catecholamine which was identified microspectrofluorometrically as dopamine. The chromaffin cells were innervated by efferent axons with typical preganglionic sympathetic terminals which were acetylcholinesterase-positive. Although the general morphology and cytochemistry agree with those of developing intra-adrenal chromaffin cells in mammals, the morphological characteristics implicate them as active secretory gland cells. The dopamine transmitter phenotype seems to be determined by the maintenance throughout life of the separate and distant location of steroidogenic interrenal tissue from suprarenal elements.

Decreased norepinephrine and epinephrine contents in chromaffin tissue of rainbow trout (Oncorhynchus mykiss) exposed to diethyldithiocarbamate and amylxanthate.

1. Rainbow trout (Oncorhynchus mykiss) were exposed to 0.5 or 5.0 microM of diethyldithiocarbamate (DDC) or amylxanthate (AX) for 24 hr. 2. Both DDC (0.5-5.0 microM) and AX (5.0 microM) significantly decreased norepinephrine and epinephrine levels in the head kidney as well as the quotients epinephrine/dopamine and/or norepinephrine/dopamine. 3. The results probably reflect an inhibition of dopamine-beta-hydroxylase, the enzyme responsible for the synthesis of norepinephrine and epinephrine from dopamine. 4. It is concluded that an exposure of fish to these complexing agents could disturb physiological processes controlled by catecholamines. 5. Diethyldithiocarbamate may prove to be a valuable pharmacological tool for the study of catecholamine function in fish.

Organization and distribution of the rat subdiaphragmatic vagus and associated paraganglia.

This experiment analyzed the organization of the rat abdominal vagus. To spare delicate tissues and preserve positional information, untrimmed blocks of the subdiaphragmatic viscera (N = 22) were fixed, impregnated by using a pyridine-silver protocol, and double embedded. Each block was sectioned transversely at 7 micron, and a section every 70 micron from the diaphragm to the cardia was analyzed. The features of the section were traced and digitized for computer reconstruction. Included in the measurements were sizes and locations of bundles, fascicles, and paraganglia. The anterior and posterior vagi were consistently distinctive in size, distribution, cross-sectional shape, and paraganglionic content. In the most common pattern (41% of animals), the anterior trunk coursed longitudinally on the ventral surface of the esophagus, giving off at successively more distal levels the hepatic branch, the accessory coeliac branch and then the bundles of the anterior gastric branch. The posterior trunk separated into a coeliac branch and a posterior gastric branch, each consisting of numerous bundles, in the most distal quarter of the esophagus. Fifty-nine percent of all animals exhibited one or more significant variations in vagal organization (e.g., double primary trunks--41%, supernumerary branches--18%, or atypical branching sequences--9%). Four to 14 vagal paraganglia (mean = 8 +/- 1; equivalent to 32/rat, corrected for sampling) were found in each animal, and no branch was consistently devoid of paraganglia. Ninety-four percent of the paraganglia were located at nerve branch points. Some of the larger paraganglia contained at their central poles one to six neurons with soma diameters ranging from 14 to 22 micron.

The functional morphology of chromaffin cells.

Based on classical and up-to-date literature, the most important morphological and histochemical characteristics of chromaffin cells are summarized. Chromaffinoblasts begin to migrate into the cortex of the adrenal in the second month of the human embryo. In adults, the polygonal cells of the medulla appear as rounded islands as well as shorter or longer cords beside sinusoidal vessels. A high variety in form of chromaffin granules was registered in the human adreno-medullary cells but author stressed that the fixation process itself can influence the shape of secretory granules. A well-developed Golgi apparatus, abundant rough-surfaced endoplasmic reticulum, a large number of mitochondria and lipofuscin pigments can be seen in the chromaffin cells. These organelles participate actively in the genesis and ultimate fate of chromaffin granules. Although exocytosis seems to be the most probable hormone-liberation process in the hamster adrenal medulla, the general validity of this process has not convincingly been proved in other species of vertebrates. The physiological effects of adreno-medullary hormones and the innervation of the gland are thoroughly discussed.

The ultrastructural organization of sympathetic ganglia of the cat.

The organization and relations between nerve, glial, chromaffin and other structural components of sympathetic ganglia of the cat were studied electron microscopically. Cholinergic, adrenergic and, probably, peptidergic terminals of axons making different contacts with the surrounding ganglionic cells and processes are shown with electron histochemical methods. Ultrastructural features of some dendrites are revealed which characterize them as sensory terminals of sympathetic ganglia. Besides the known axo-dendritic, axo-somatic and axo-axonal synapses, the ganglia show axo-glial synapses, and also dendro-dendritic and dendro-somatic contacts. It is established that preliminary destruction of ganglionic connections with the central nervous system is fatal only to a proportion of these interneuronal contacts while the rest of them persist. Synaptic complexes are found showing contacts of several axons and dendrites and representing a morphological substrate for convergence and divergence. No synapses are found whose presynaptic pole would be formed by a chromaffin cell. The functional role of these cells in the ganglia is discussed.

Age related increase in catecholamine-containing paraganglia in male Fischer-344 rats.

For identification of paraganglia (PG), samples of para-aortic tissue, tissues containing the coeliac-mesenteric ganglion complex, and the hypogastric ganglia were removed from 3- and 33-month-old male Fischer-344 rats and were processed by the formaldehyde-induced fluorescence method for visualization of catecholamines. Small PG containing 5-30 cells per section were found consistently in young animals. In each of six old rats, large PG containing 500-4000 brightly fluorescent cells per section were detected. Cell counting revealed a 13.5 x increase in number of PG cells between 3- and 33-month-old rats. Microspectrofluorimetric quantitation in old rats showed equal amounts of catecholamines in PG cells and in adrenal medullary cells. Most PG were located in samples from the para-aortic area.

[Development of the adrenergic innervation of the atrioventricular valves of certain vertebrates]. / Razvitie adrenergicheskoi innervatsii atrioventrikuliarnykh klapanov serdtsa u nekotorykh pozvonochnykh.

Adrenergic innervation of the atrioventricular valves in the carp Cyprinus carpo, frog Rana temporaria, tortoise Emys orbicularis, hens and albino rats has been investigated by histochemical glyoxylic technique. It was shown that the adrenergic innervation of cardiac valves becomes more intense and more complex during progressive evolution of cardio-vascular activity. Adrenergic nerves realize the connection between annullus fibrosus, valve, chordal tendineal and papillary muscles. Chromaffin cells of the valve serve as an additional store of catecholamines. A possibility cannot be excluded that these cells supply with biogenic amines the papillary muscles regulating their activity.

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.

The endocrine nature of the paranganglia of man.

Brightly fluorescent paraganglia were found in the retroperitoneal tissue of adult man. The histofluorescence properties of the paraganglia indicate the presence of tryptophyl peptides, which might be of endocrine importance.

Histochemical light microscopic study of catecholamine containing paraganglia in the human pelvis.

Histological and histochemical techniques have been employed to determine the structure and autonomic innervation of paraganglia located in the human pelvis. In foetal and early postnatal tissues, paraganglia formed rounded cellular masses which were frequently in company with the autonomic nerves and ganglia of the urinary bladder and other pelvic viscera. The constituent cells contained only small amounts of cholinesterase and were unrelated to enzyme positive autonomic nerves; acetylcholinesterase containing nerves were occasionally observed in the capsule and the fibrous septa of the pelvic paraganglia. In early postnatal specimens, pelvic paraganglia frequently contained single or multiple "pacinian-like" corpuscles, each possessing a central region which was rich in both acetyl and pseudocholinesterase. These structures were rarely observed within autonomic ganglia and were absent 4 1/2 years post partum. By means of a histochemical technique, pelvic paraganglia were found to contain catecholamine which was attributed to the presence of relatively large quantities of noradrenaline. These observations have been discussed with particular reference to the results of other studies on the autonomic innervation of paraganglia.

Studies on the seasonal histocytological changes in the internal and chromaffin cells of male Puntius sophore (Ham) in relation to its reproductive cycle.

An attempt has been made to correlate the activities of interrenal and chromaffin cells with the reproductive cycle of Puntius sophore. Chromaffin cells do not have any significant bearing while interrenal cells undergo qualitative and quantitative changes which have been correlated with the various phases in the reproductive cycle of this fish. These cells undergo degranulation and vacuolisation during spawning phase, disorganisation during regression phase, and reorganisation and gradual growth during resting and prespawning phases. These cells thus appear to play an important role in the reproductive physiology of this fish.

Abdominal vagal paraganglia: distribution and comparison with carotid body, in the rat.

A study was made of the distribution of abdominal vagal paraganglia in the gastro-oesophageal region of 12 rats. In all rats 4-40 paraganglia were found embedded in, or closely associated with, the vagus nerves and their branches. The paraganglia consisted of groups of rounded, weakly chromaffin-positive cells surrounded by flattened cells and supplied by small nerves and blood vessels. The paraganglia were morphologically identical to simultaneously fixed carotid body tissue and showed similar fluorescence characteristics.