The relationship between platelet and megakaryocyte volumes.

Planimetric megakaryocyte and nuclear areas were measured by histological techniques in rabbits subjected to 6 days of thrombocytopenia and in normal steady state function. A theoretical correction factor enables an estimate to be obtained of the actual megakaryocyte, megakaryocyte cytoplasm and nuclear volumes in these two states. The corresponding platelet volumes after 6 days of thrombocytopenia and in normal function were also measured. This enables the number of platelets produced by a single megakaryocyte (on average) to be computed directly in the two states of platelet production. The experiments showed that the volume of megakaryocyte cytoplasm increased significantly in stimulated platelet production. The number of platelets produced per megakaryocyte doubled and the mean platelet volume also increased during stimulated production. An explanation is given for the observed behaviour of platelet and megakaryocyte volumes.