Megakaryopoiesis in the spleen, day 28 after transplantation.

Megakaryocytes stain dark as a consequence of histochemical staining for acetylcholinesterase. (A) Typical spleen of animal receiving Rho^low stem cells. (B) A cluster of megakaryocytes in the perifollicular space after Rho^low transplantation. (C) Animals receiving the Rho^high progenitor have almost no splenic megakaryocyte activity. Original magnification A, × 20; B, × 100; and C, × 20.