Ultrastructural effects of granulocyte colony stimulating factor (G-CSF) and macrophage colony stimulating factor (M-CSF) on rat neutrophils and monocytes

Human granulocyte colony stimulating factor (G-CSF) and macrophage colony stimulating factor (M-CSF) were administered intravenously to rats, and their effects on neutrophils and monocytes were examined by electron microscopy. G-CSF increased the number of cytoplasmic granules in neutrophils. It also enhanced maturation of the nuclear shape in the neutrophils, while chromatin condensation and peroxidase distribution remained immature. M-CSF induced proliferation of monocytes in peripheral blood and bone marrow, but did not affect morphology or distribution of peroxidase reactivity.