Figure 1. Timing of hematopoietic maturation across species.
The relative timing of hematopoiesis at specific anatomic sites in the human (blue), mouse (red), and zebrafish (green) are shown. Although the pace of hematopoietic maturation varies in each organism, hematopoiesis matures in highly conserved patterns through analogous organs prenatally and postnatally, with primitive hematopoiesis occurring in extraembryonic mesoderm derived cells.