This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Cells in the aoa gonad mesonephros region is associated with: 
Select and explain. 
A. Hematopoeisis, B. Immunity, C. Neural tube formation, D. None of the above
A: Hematopoeisis
Answer: A: Hematopoeisis 
Explanation: 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: Langman's embryology 11th edition Chapter 7.