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PubMed1989

The cytoplasmic matrix of the adrenal chromaffin cells of rats under normal and stressed conditions.

In embedment-free electron microscopy with polyethylene glycol embedding and subsequent deembedding, the conventional cytoplasm of the chromaffin cells was revealed to consist of a three-dimensional lattice of microtrabeculae and gives the impression that the chromaffin granules are held in place by the lattice. After the restraint stress, a substantial number of chromaffin cells were almost free of granules, and the microtrabecular lattice was much more compact than that in cytoplasmic regions occupied with remaining granules or increased mitochondria. In immunocytochemistry, actin immunofluorescence was confined to the subplasmalemmal regions, while tubulin and tropomyosin immunofluorescence appeared throughout the entire cytoplasm of normal chromaffin cells. After the stress, the immunofluorescence for actin and tubulin increased in intensity, while that for tropomyosin decreased. Immunogold labelings for actin and tubulin were found mainly on the thinner subplasmalemmal microtrabeculae and the thicker perikaryal ones, respectively, while some were deposited in the form of small aggregates on portions of microtrabeculae. No specific association between the gold labelings for actin or tubulin and the chromaffin granules was found, even in the subplasmalemmal regions. A hypothetical interpretation was proposed in which a more compact lattice of the microtrabeculae in spatial association with a looser lattice represents a gelated state of the cytoplasm. The significance of the gel-sol transition of the cytoplasmic matrix in relation to the secretory mechanism was discussed.

Animals↗
PubMed1976

Tumours of the adrenal gland and paraganglia.

This classification is arranged in two parts in order to take into account the different origins, structures, and functions of the cortex and medulla. The tabular classification is a simplified version of that suggested for adrenal tumours in man, and includes cortical adenoma and carcinoma, phaeochromocytoma, chemodectoma, neurofibroma, ganglioneuroma and ganglioneuroblastoma, and neuroblastoma. A detailed functional classification is not given, since the hormonal activity of many adrenal tumours in animals is less well known than it is in man. Of the tumour-like lesions listed, cortical hyperplasia is particularly important in several species.

Adrenal Gland Neoplasms↗
PubMed1985

Immunohistochemical evidence for the occurrence of vasoactive intestinal polypeptide (VIP)-containing nerve fibres in human fetal abdominal paraganglia.

The abdominal paraganglia in man represent a major source of catecholamines, and perhaps peptide hormones, during the fetal period. The nature of the innervation of the abdominal paraganglia was studied immunohistochemically by utilising antibodies to vasoactive intestinal polypeptide, enkephalin, substance-P and somatostatin. The paraganglia showed an abundant network of VIP-immunoreactive fibres, and similar nerve fibres were found within nerve bundles of the preaortic sympathetic plexus. Occasionally, VIP-immunoreactive fibres were seen within the prevertebral ganglia, but stained cell bodies were never observed. It may be suggested that VIP-containing nerves could regulate a secretory response from fetal human abdominal paraganglia.

Chromaffin System↗
PubMed1984

The human sympathochromaffin system.

Hypoglycemia stimulates adrenomedullary epinephrine secretion; standing stimulates sympathetic neural norepinephrine release. In five bilaterally adrenalectomized persons plasma epinephrine, measured with a sensitive single-isotope derivative assay, rose from 15 +/- 2 to 35 +/- 7 pg/ml (P less than 0.02) during hypoglycemia but did not increase during standing. In contrast, plasma norepinephrine rose during standing but not during hypoglycemia. Thus, in humans 1) extra-adrenal epinephrine secretion is regulated and derived from innervated cells other than sympathetic postganglionic neurons; 2) because the plasma levels of epinephrine in adrenalectomized individuals even in response to the potent stimulus of hypoglycemia are below physiological thresholds, any biological actions of extra-adrenal epinephrine in adults must be paracrine rather than endocrine in nature; 3) hypoglycemia does not appear to stimulate the sympathetic nervous system. In view of these findings, we propose that extra-CNS catecholamine-producing tissues be termed the sympathochromaffin system consisting of two components: 1) the sympathetic nervous system that releases the neurotransmitter norepinephrine from its postganglionic neurons, and 2) the chromaffin tissues, including the adrenal medullae, that contain cells that secrete epinephrine, norepinephrine, or dopamine. The plasma epinephrine concentration is a valid measure of its chromaffin tissue (predominantly adrenomedullary) secretion, whereas the plasma norepinephrine concentration is an index of sympathetic neuronal activity under some but not all conditions.

Adrenal Medulla↗