RESUMEN
The human adult adrenal cortex is composed of the zona glomerulosa (zG), zona fasciculata (zF), and zona reticularis (zR), which are responsible for production of mineralocorticoids, glucocorticoids, and adrenal androgens, respectively. The final completion of cortical zonation in humans does not occur until puberty with the establishment of the zR and its production of adrenal androgens; a process called adrenarche. The maintenance of the adrenal cortex involves the centripetal displacement and differentiation of peripheral Sonic hedgehog-positive progenitors cells into zG cells that later transition to zF cells and subsequently zR cells.
Asunto(s)
Corteza Suprarrenal/embriología , Diferenciación Celular , Células Madre , Corteza Suprarrenal/crecimiento & desarrollo , Corteza Suprarrenal/metabolismo , Andrógenos/metabolismo , Glucocorticoides/metabolismo , Proteínas Hedgehog/metabolismo , Humanos , Mineralocorticoides/metabolismo , Pubertad/metabolismo , Células Madre/metabolismo , Zona Fascicular/embriología , Zona Fascicular/crecimiento & desarrollo , Zona Fascicular/metabolismo , Zona Glomerular/embriología , Zona Glomerular/crecimiento & desarrollo , Zona Glomerular/metabolismo , Zona Reticular/embriología , Zona Reticular/crecimiento & desarrollo , Zona Reticular/metabolismoRESUMEN
UNLABELLED: With 14 figures and 3 tables SUMMARY: Each adrenal gland consisted of cortex and medulla that developed from different embryological origins and presented different cellular organization. One hundred male or female camel embryos or fetuses with crown vertebral rump lengths (CVRL) that ranged from 0.8 to 117 cm were examined. The adrenal cortex, which is derived from intermediate mesoderm, was first observed in the 0.8-cm CVRL camel embryo. The adrenal cortex initially was combined with the gonad as a thickened region of proliferating cells derived from splanchnic intermediate mesoderm. Adrenocortical tissue was first separated from the gonadal tissue in the 2-cm CVRL camel fetus and was observed as a separate dorso-medial mass of cells. At 2.5-cm CVRL, the adrenocortical tissue was surrounded by a capsule of undifferentiated mesenchymal cells, except at its proximal pole, where an invagination was located through which chromaffinoblast cells entered the cortex. The chromaffinoblast cells migrated from the neural crest to form the medulla of the developing adrenal gland. In the 3.5-cm CVRL camel fetus, the adrenocortical cells differentiated into two layers: the inner fetal cortex and the outer definitive cortex. As development proceeded, the fetal cortex degenerated and the definitive cortex formed the zona glomerulosa and zona fasciculata. The zona reticularis did not form until the end of gestation. During prenatal life, the adrenal medulla was much thicker than the cortex.
Asunto(s)
Glándulas Suprarrenales/embriología , Camelus/embriología , Corteza Suprarrenal/anatomía & histología , Corteza Suprarrenal/embriología , Médula Suprarrenal/anatomía & histología , Médula Suprarrenal/embriología , Animales , Diferenciación Celular , Embrión de Mamíferos , Desarrollo Fetal , Feto/embriología , Mesodermo/anatomía & histología , Mesodermo/embriología , Zona Fascicular/anatomía & histología , Zona Fascicular/embriología , Zona Glomerular/anatomía & histología , Zona Glomerular/embriología , Zona Reticular/anatomía & histología , Zona Reticular/embriologíaRESUMEN
In an attempt to elucidate the mechanism(s) through which the functional adrenal cortex is established, we analyzed immunohistochemically the expression of various markers for the adrenocortical zones, i.e. the zona glomerulosa (zG), the zona fasciculata (zF), and the zona reticularis (zR), as well as markers for the medulla, and further examined the distribution and behavior of DNA-synthesizing cells in rat adrenal glands during development. The results showed that 1) separation of the cortex and medulla, and the development of functional zonation in the cortex began at around the time of birth, 2) at fetal stages when cortical zonation was not established, DNA-synthesizing cells were found scattered throughout the gland, where they proliferated without significant migration, and 3) after birth in the adrenal cortex with established cortical zonation, DNA-synthesizing cells were localized near the undifferentiated zone between zG and zF, and then they migrated centripetally. Cell death appeared to occur in the innermost portion of the cortex, where many resident macrophages are present. These findings illustrate basic processes underlying adrenal development and suggest that the undifferentiated region is apparently the stem cell zone of the adrenal cortex that maintains the cortical zonation.