In human beings, it is rudimentary, appears at the end of the third week ( day 20 ) and replaced by mesonephros after 3.5 weeks.
22.
During this time primordial germ cells migrate from the yolk sac to the gonadal ridge; a region of mesenchyme arising from, and running parallel with, the mesonephros.
23.
These embryonic structures are on either side; the pronephros, the mesonephros and the metanephros of the kidney, and the Wolffian and M�llerian ducts of the sex organ.
24.
I guess it's safe to assume that at the larval stage it's a pronephros, but does it change to a mesonephros at a later stage?
25.
It contains the dorsal aorta, genital ridges and mesonephros and lies between the notochord and the somatic mesoderm, extending from the umbilicus to the anterior limb bud of the embryo.
26.
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.
27.
This is the same case in human embryos, where they are first detected at day 27 in the aorta gonad mesonephros region, expand rapidly at day 35, then disappear at day 40.
28.
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.
29.
The Wolffian body operates as a kidney ( mesonephros ) in fishes and amphibians, but the corresponding tissue is co-opted to form parts of the male reproductive system in other classes of vertebrate.
30.
In mammalian embryology, the first definitive HSCs are detected in the AGM ( aorta-gonad-mesonephros ), and then massively expanded in the fetal liver prior to colonising the bone marrow before birth.
