DNA metabolism and development of organelles in guinea-pig megakaryocytes: a combined ultrastructural, autoradiographic and cytophotometric study

The thick and thin section technique was used to combine ultrastructural studies of guinea-pig megakaryocytes with either autoradiographic studies of thymidine incorporation into megakaryoblast DNA or cytophotometric determination of megakaryocyte ploidy. Megakaryocytes engaged in polyploidization already showed granule and some demarcation membrane formation. The polyploidization phase stopped at the 8N, 16N, or 32N level after 3 plus or minus 0.5 (1 SD) genome duplications.