Genetic and physiological variations in megakaryocyte DNA content distributions

The DNA content of normal megakaryocytes usually ranges from 8N to 64N, with 16N as the modal DNA content. The frequency of cells at each DNA content can be altered by experimental induction of thrombocytopenia, thrombocytosis or marrow ablation, and in various disease states; however, the mechanisms and regulation involved in the process of polyploidization remain obscure. This discussion will focus on genetic and physiologic variations in megakaryocyte DNA content distributions. The genetic variations are those we have observed among mouse strains, with the most pronounced present in several C3H substrains in which the modal megakaryocyte DNA content is 32N, rather than 16N. The physiologic variation reported here is a shift to the right in megakaryocyte DNA content distributions during late pregnancy in the rat.