In Embryonic Development
The AGM region is derived from the mesoderm layer of the embryo. During organogenesis (around the fourth week in human embryos), the visceral region of the mesoderm, the splanchnopleura, transforms into distinct structures consisting of the dorsal aorta, genital ridges and mesonephros. For a period during embryonic development, the dorsal aorta produces hematopoietic stem cells, which will eventually colonise the liver and give rise to all mature blood lineages in the adult. By birth, the dorsal aorta becomes the descending aorta, while the genital ridges form the gonads. The mesonephros go on to form nephrons and other associated structures of the kidneys.
The formation of the AGM region has been best described in non-mammalian vertebrates such as Xenopus laevis. Shortly after gastrulation, cells from the dorsolateral plate, analogous to the splanchnopleura mesoderm in mammals, migrate to the midline, beneath the notochord to form the dorsal aorta, and laterally the cardinal veins and nephric ducts.
Read more about this topic: Aorta-gonad-mesonephros
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