Serotonin uptake by progeny of murine megakaryocyte precursors (CFU-M) in vitro.

Normal megakaryocytes take up and store serotonin (5-hydroxytryptamine) (5-HT). Murine megakaryocyte colonies were grown in plasma clot cultures, labeled autoradiographically with 3H-5-HT-creatinine sulfate, and stained for acetylcholinesterase. Silver granules representing serotonin uptake were present over almost all acetylcholinesterase-positive cells, including both mature megakaryocytes and smaller mononuclear cells. There was no evidence of serotonin accumulation in non-acetylcholinesterase staining granulocytic, monocytic, or erythroid cells. The results of this study provide: (a) a new label to identify murine megakaryocytes and smaller mononuclear megakaryocyte precursors (progeny of CFU-M) in plasma clot cultures, (b) further evidence that immature acetylcholinesterase-positive megakaryocyte precursor cells possess the ability to take up and store serotonin, and (c) evidence that this function of megakaryocytes and megakaryocyte precursors is preserved in the artificial environment of plasma clot cultures.