<prompt> Cells in the aoa gonad mesonephros region is associated with:HematopoeisisImmunityNeural tube formationNone of the above  <response>: The definitive hematopoietic stem cells are derived from mesoderm surrounding the aoa in a site near the developing mesonephric kidney called the aoa-gonad-mesonephros region AGM. These cells colonize the liver, which becomes the major hematopoietic organ of the embryo and fetus from approximately the second to seventh months of development. Stem cells from the liver colonize the bone marrow, the definitive blood-forming tissue, in the seventh month of gestation, and thereafter, the liver loses its blood-forming function. Ref: Langmans embryology 11th edition Chapter 7. 