Mitotic index modifications in a series of gliomas related to degree of malignancy

: We have measured on semi-thin sections, the mitotic index in 5 benign gliomas and 5 malignant gliomas among a whole of about 80,000 cells in each group, divided into fields of 750 cells on an average. We have differentiated between normal mitoses and abnormal mitoses on one hand, between viable and adequate mitoses and non-viable mitoses on the other. If we take into account the total number of mitoses, the mitotic index is not greatly different between the 2 groups of tumors (about 5 per thousand), although slightly superior in the benign gliomas. If we take into account the viable or adequate mitoses only, the mitotic index is greatly superior among the benign gliomas. These results are discussed according to other data related with the kinetics of proliferation of gliomas and according to the possibility of cellular fusions as a process of a minor spreading of malignant gliomas.