Journal ArticleDOI
Different types of small granule-containing cells and neurons in the guinea-pig adrenal medulla.
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TLDR
Two types of neurons were present in the guinea-pig adrenal medulla, one resembling the principal neurons in sympathetic ganglia, the other, which, according to its morphology, occupied an intermediate position between principal neurons and SGC cells.Abstract:
An electron microscopic, histo- and biochemical study was carried out on the adrenal medulla of newborn and adult guinea-pigs giving special emphasis to small granule-containing (SGC) cells. Adrenaline (A) was the predominating catecholamine (CA) both in newborn (70-90% of total CA) and adult (85-90%) guinea-pig adrenals. In analogy to the biochemical findings electron microscopy revealed a high predominance of A cells, which contained large granular vesicles with an average diameter of 180 nm. Most noradrenaline (NA) storing cells showed granular vesicles of a considerably smaller average diameter (80 nm) and had a higher nuclear-cytoplasmic ratio. These cells were termed SGC-NA cells. NA cells with large granular vesicles (average diameter 170 nm) were extremely rare. Another type of SGC cells contained granular vesicles with cores of low to medium electron-density (SGC-NA-negative cells). Biochemical determinations made it unlikely that these cells contained predominantly dopamine (DA). SGC cells were scarcely innervated by cholinergic nerves. They formed processes, which were found both in the adrenal cortex and medulla contacting blood vessels including sinusoid capillaries, steroid producing cells of the reticularis and fasciculata zone and processes, which were interpreted to belong to medullary nerve cells. Two types of neurons were present in the guinea-pig adrenal medulla, one resembling the principal neurons in sympathetic ganglia, the other, which, principal neurons and SGC cells. In adrenomedullary grafts under the kidney capsule, which were studied three weeks after transplantation, "ordinary" A cells resembled SGC-NA negative cells with respect to their ultramorphology. Processes of transplanted principal neurons showed uptake of 5-hydroxydopamine and, hence, were considered to be adrenergic. Despite the lack of extrinsic nerves to the transplants, few principal neurons received cholinergic synapses, the origin of which is uncertain to date.read more
Citations
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References
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Control of Enzymatic Synthesis of Adrenaline in the Adrenal Medulla by Adrenal Cortical Steroids
TL;DR: The activity of phenylethanolamine N- methyltransferase, the enzyme that catalyzes the N-methylation of noradrenaline to form adrenaline, falls following hypophysectomy, and can be restored by injections of adrenocorticotropic hormone (ACTH) or of dexamethasone, a potent synthetic glucOCorticoid.
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Dopamine-sensitive adenyl cyclase: possible role in synaptic transmission.
John W. Kebabian,Paul Greengard +1 more
TL;DR: The results suggest that the physiological effects of dopamine in the ganglion, and possibly elsewhere in the nervous system, may be mediated by stimulating the synthesis of adenosine 3',5'-monophosphate.