Murine myeloid leukemia: colony formation in vitro.

Normal and myeloid leukemic spleen cells from RF mice were cultured in vitro in plasma clots. In situ histochemical staining and karyotypic analysis of the colonies formed in the clot revealed that the colonies produced by leukemic and normal progenitors were indistinguishable morphologically and cytochemically. Colonies of leukemic origin were identified by in situ karyotypic analysis, a method not previously utilized in studies of hematopoietic proliferation in semi-solid matrices.