Adult rats 4--5 months old and 150--200g in body weight were used in this experiment.Lesions were made with antiseptic precaution by excising portions (0.7×0.4×0.1cm) of thecerebral cortices under ether anesthesia. The animals were sacrificed by decapitation at thetime intervals ranging from 1 to 30 days after the operation. Specimens of the brain wereremoved from the lesions with their adjacent normal areas, and processed for histological andhistochemical studies. Mitotic figures were observed in nerve cells adjacent to the lesions. The mitotic processof these neurons is similar to that of the other tissue cells, as it can also be divided into fourstages--prophase, metaphase, anaphase and telophase. However, neurons are entirely dif-ferent from the neuroglia and other tissue cells in that these have characteristic cell pro-cesses, i. e. axon and dendrites, while most of the neurons are pyramidal cells of layers Ⅱand Ⅴ of the cerebral cortex. The other characteristic feature is that the dividing neuroncontains Nissl bodies in the cytoplasm. Adult rats 4-5 months old and 150--200g in body weight were used in this experiment. Lesions were made with antiseptic precaution by excising portions (0.7 × 0.4 × 0.1 cm) of the cerebral cortices under ether anesthesia. The animals were sacrificed by decapitation at thetime intervals ranging from 1 to 30 days after the operation. Specimens of the brain wereremoved from the lesions with their adjacent normal areas, and processed for histological and histochemical studies. Mitotic figures were observed in nerve cells adjacent to the lesions. The mitotic processof these neurons is similar to that of the other tissue cells, as it can also be divided into fourstages - prophase, metaphase, anaphase and telophase. However, neurons are entirely dif-ferent from the neuroglia and other tissue cells in that these have characteristic cell pro-cesses, ie axon and dendrites, while most of the neurons are pyramidal cells of layers Ⅱ and Ⅴ of the cerebral cortex. The other characteristic feature is t hat the dividing neuroncontains Nissl bodies in the cytoplasm.