Abstract
Marrow was cultured on chick plasma clots, glass surfaces and in suspension and the influence of various metabolites and antimetabolites on the growth and differentiation of red cell precursors was studied.
Vitamin B12 appeared to stimulate cell growth in cultures grown on clots and to convert megaloblastic hematopoiesis to normoblastic in cultures grown on glass.
In suspension cultures of megaloblastic marrows in pernicious anemia serum significant cell increases were obtained with the addition of folinic acid, but not with vitamin B12. Both vitamin B12 and folinic acid appeared to accelerate the conversion of megaloblasts to normoblasts in differential counts of stained smears of such cultures. No enhancing effect of intrinsic factor upon the activity of B12 in suspension cultures of megaloblasts was observed. The effect of folinic acid could be blocked by colchicine and folinic acid could reverse the inhibitory effects of Amethopterin. These facts indicated that folinic acid acted in suspension cultures by stimulating mitosis.
Megaloblasts could be produced from normoblastic marrows by culturing them in pernicious anemia serum, or in normal serum in the presence of Amethopterin.
