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The aorta-gonad-mesonephros (AGM) region is an area derived from splanchnopleura mesoderm identified in embryonic humans, mice, and non-mammalian vertebrates such as birds and zebrafish. It contains the dorsal aorta, genital ridges and mesonephros and lies between the notochord and the somatic mesoderm, extending from the umbilicus to the ...
Hematopoietic stem cells (HSCs) are the stem cells [1] that give rise to other blood cells.This process is called haematopoiesis. [2] In vertebrates, the first definitive HSCs arise from the ventral endothelial wall of the embryonic aorta within the (midgestational) aorta-gonad-mesonephros region, through a process known as endothelial-to-hematopoietic transition.
It is expressed in all haematopoietic sites that contribute to the formation of haematopoietic stem and progenitor cells , including the yolk sac, [22] allantois, placenta, para-aortic splanchnopleura (P-Sp; (the visceral mesodermal layer), [23] aorta-gonad-mesonephros (AGM) and the umbilical and vitelline arteries. [24]
Hematopoiesis also takes place in many other tissues or organs such as the yolk sac, the aorta-gonad mesonephros (AGM) region, and lymph nodes. During development, vertebrates go through a primitive and a definitive phase of hematopoiesis. The lungs also play a role in platelet production in adults. [5]
Another proposed source of mesoangioblasts comes from a region underneath the aortic floor endothelium, termed the human Aorta-Gonad-Mesonephros (AGM) region, where hematopoiesis occurs. This theory describes that mesoangioblasts act as the precursors to certain cells in this region, as there is a possibility of a hematopoiesis-supporting ...
During mouse embryonic development, specific (medium) expression levels of CD27 (in addition to high cKit, [7] [8] medium Gata2, [9] [10] [8] and high CD31 [8] expression levels) define the very first adult definitive hematopoietic stem cells generated in the aorta-gonad-mesonephros region. [8]
The mesonephros is involved in the development of the testis, but its role is in differentiation, and not determination. This is indicated by the absence of SRY expression in the mesonephros. SRY expression is expressed exclusively in the developing gonad, lacking a presence in any other tissue in embryos or adults. [2]
The mesonephros persists and forms the anterior portion of the permanent kidneys in fish and amphibians, but in reptiles, birds, and mammals, it atrophies and for the most part disappears rapidly as the permanent kidney (metanephros) begins to develop [2] during the sixth or seventh week. By the beginning of the fifth month of human development ...