Kidneys with a complete parenchymal bridge in the sinus, which is diagnostic for a duplex collecting system, were also excluded from the study. The children were between 1 month and 18 years old (mean age, 6.1 Â± 5.9 years).he objective of our study was to develop, by use of ultrasound, nomograms of renal parenchymal thickness, medullary pyramid thickness (height), renal length, and the ratio of medullary pyramid thickness to parenchymal thickness in healthy children.
erythropoietin. a glycoprotein hormone secreted by the kidney in the adult and by the liver in the fetus, which acts on stem cells of the bone marrow to stimulate red blood cell production (erythropoiesis).
Hormonal Regulation of Hormone Release. Hormonal regulation of hormone release involves a hormone binding to its receptor on an endocrine cell to regulate hormonal secretion. A hormone that stimulates hormone secretion is called a tropic hormone. Tropic hormones may also stimulate proliferation of endocrine cells.or polar hormones, tropic hormones stimulate endocrine secretion by stimulating cell secretion; that is, exocytosis. An example is the regulation of growth hormone (GH) secretion by the tropic hormone growth hormone releasing hormone (GHRH) . GHRH is a hypophysiotropic hormone.