Variations in Mitotic Activity of Rat Bone Marrow under Various Conditions

抄録

1. As a continuation of the previous study of normal bone marrow, the influences of starvation, the repetition of bleeding and the parenteral administration of typhoid vaccine on the rate of cell production in the bone marrow of young mature albino rats have been investigated, using the colchicine method.
2. At 8-11 days of fasting, the ab s olute number of mitotic figures of the nucleated red cells, together with the erythroid cell population, was greatly reduced. The mitotic rate of the granulocytes as well as the myeloid cell population in the bone marrow did not show any remarkable changes.
3. Daily withdrawal of 2.0 -2.7 ml of blood by heart puncture produced, on the other hand, a considerable increase not only in the cell population but also in the mitotic rate of the nucleated red cells in the bone marrow. A maximal value of the mitotic index of these cells was about 300 per cent of normal at 5 days after the initiation of bleeding. The mitotic activity of the granulocytes in the bone marrow remained almost unchanged.
4. After the intraperitoneal i n jection of the Typhoid-Paratyphoid Vaccine (Takeda) in a dose of 0.4 ml per 100 g body weight, there occurred a marked neutrophilic leukocytosis with a simultaneous rise of the mitotic index of the granulocytes in the bone marrow, the neutrophils in particular, reaching its maximum at 12 hours after injection. By that time, the mitotic index of these cells rose to 500 to 600 per cent of normal value. However, the cell population of the granulocytic series did not appear to increase after injection.