Surface ultrastructure of human megakaryocytes sorted on the basis of DNA content

The relationship of polyploidization (DNA content) to differentiation is not well defined. We have developed centrifugal elutriation and Percoll density gradient centrifugation to obtain large numbers of highly-purified megakaryocytes which subsequently were stained for DNA content with Hoechst 33342 and sorted by FACS into 8C, 16C and 32C ploidy classes for correlated analysis of cell surface structures by scanning electron microscopy. Each ploidy class revealed unique surface characteristics that reflect differentiation occurring in megakaryocytes independent of their DNA content.