The origin of mast cells
Hematopoietic cells arise in several temporally distinct waves during
prenatal development. The first MCs originate from primitive
erythromyeloid progenitors in the extraembryonic yolk sac31-34. A second wave of MCs appears together with the
first definitive hematopoietic progenitors. The first two waves mainly
contribute to connective tissue MCs (CTMC) and serosal-type MCs32. The third hematopoietic wave originates from the
aorta-gonado-mesonephros region. Cells formed during this wave produce
hematopoietic stem cells that exhibit MC-forming potential32. It was for a long time assumed that MCs develop
from hematopoietic stem cells in the bone marrow 35.
However, it is now clear that bone marrow hematopoietic stem cells
produce a fraction, but not all, MCs. Experiments also show that bone
marrow-derived MCs mainly replenish the mucosal MC population
postnatally 32. However, there is a redundancy in the
potential of the waves as bone marrow-derived MCs can reconstitute
depleted skin-resident (connective tissue-type) MCs and populate the
skin following inflammation 36.