ZONA GLOMERULOSA FULL

Later, Gottschau (1883) was the first to suggest that adrenocortical cells originate in the outer part of the gland, and migrate centripetally, thus becoming phenotypically glomerulosa, then fasciculata and reticularis in sequence. The nature and significance of the zonation of the mammalian adrenal cortex has attracted considerable interest during the fifteen decades following the first description of its three main zones, zona glomerulosa, zona fasciculata, and zona reticularis, by Arnold (1866). In these and other ways it more and more appears that the functions of the gland should be viewed as an integrated whole, greater than the sum of its component parts. Furthermore, throughout the cortex local regulatory factors, including cytokines, catecholamines and the tissue renin-angiotensin system, modify and refine the effects of the systemic trophic factors. It is known that in development, recruitment of stem cells is stimulated by signals from within the glomerulosa.

Nor, in the rat anyway, does it express MC2R to account for the response of aldosterone to ACTH.

ZONA GLOMERULOSA FULL

This is particularly true of the glomerulosa, which does not seem to have the full suite of enzymes required for aldosterone biosynthesis.

Perhaps more importantly, neither the distribution of enzymes nor receptors suggest that the individual zones are necessarily autonomous in their production of steroid. Firstly, proliferation can take place throughout the gland, and although the stem cells are certainly located in the periphery, zonal replenishment can take place within zones. Recent progress in understanding the development of the gland and the distribution of steroidogenic enzymes, trophic hormone receptors, and other factors suggests that this model needs refinement. Finally, the cells of the cortex originate from a stem cell population in the outer cortex or capsule, and migrate centripetally, changing their phenotype as they progress through the zones. Moreover, each zone has its specific mechanism of regulation, though ACTH has actions throughout. The standard model of adrenocortical zonation holds that the three main zones, glomerulosa, fasciculata, and reticularis each have a distinct function, producing mineralocorticoids (in fact just aldosterone), glucocorticoids, and androgens respectively. School of Biological and Chemical Sciences, Queen Mary University of London, London, UK.These results demonstrate a variety of situations where changes in intracellular are dissociated from those in corticosterone output and indicate that intracellular cannot be the sole mechanism regulating steroidogenesis under these conditions. However, this concentration of ouabain also inhibited steroidogenesis in fasciculata cells.Ħ. Ouabain at 5×10 −4 mol/l further depressed intracellular of glomerulosa cells and inhibited basal and stimulated corticosterone output. Similar results were obtained with fasciculata cells.ĥ. Ouabain at 10 −5 mol/l depressed the intracellular of glomerulosa cells but did not alter basal or stimulated corticosterone output. However, a similar increase in intracellular K + also occurred in high-potassium medium with zona fasciculata cells, whose steroid output is unresponsive to external potassium concentration ().Ĥ. In high-potassium medium (final concentration 84 mmol/l), parallel increases in intracellular K + and corticosterone output were observed with both unpurified and purified zona glomerulosa cells. Similarly, with zona glomerulosa cells purified by unit gravity sedimentation, no change in intracellular K + was detected after stimulation of steroidogenesis with serotonin or angiotensin II.ģ. Intracellular K + of unpurified zona glomerulosa cells was not altered after stimulation of corticosterone output with serotonin. Intracellular K + content, water spaces and corticosterone output were measured in isolated zona glomerulosa and zona fasciculata-reticularis cell suspensions of rat adrenal cortex, after incubations in vitro under conditions designed to alter steroidogenesis.Ģ.

Zona glomerulosa