Morphological examinations of murine granulocyte/macrophage colonies grown in serum-free cultures.

Murine bone marrow granulocyte/macrophage progenitor cells proliferated to form colonies consisting of their progeny in serum-free agar cultures in the presence of colony-stimulating activity. The cloning efficiency for the serum-free cultures was 80% of that for control cultures containing 20% fetal calf serum. Examinations of the cellular compositions of individual colonies revealed that the number of pure macrophage colonies was indistinguishable in the two culture systems while that of pure granulocyte and granulocyte/macrophage mixed colonies was smaller in the serum-free cultures.