Different forms of megakaryocytes are found in the intact spleen of rats, with ring-like nucleus and in the form of multinuclear large cells. The division of megakaryocytes takes place by multipolar mitosis without any subsequent cytotomy. During the regeneration the megakaryocyte count and their mitotic activity displayed a sharp increase. The gravitation overload increased the megakaryocyte count and their mitotic activity even more. The use of the spleen extracts against the background of gravitation overload diminished the megakaryocyte count, but increased their mitotic activity. In hypokinetic conditions the number of megakaryocytes was sharply decreased and no mitoses were seen in these cells.
Animals Cell Differentiation