Increase in Number of Nuclei and Mitotic Activity of Parenchymal Cells of the Rat Liver in Postnatal Growth

Abstract

A formula for determining the theoretical mitotic index of parenchymal cells of rat livers during post-natal growth is given as[image] where N1 is the number of parenchymal nuclei at the beginning of the growth period under consideration, N2 is the number of all the progeny nuclei derived from N1, t is the average mitotic time in minutes, and T is the length of the time of the growth period in days. The calculated changes in the mitotic index through various growth changes agrees fairly well with those established by microscopic observations, but the former gives considerably lower values. The reason for the discrepancy is not clear. The low mitotic activity of hepatic cells in adult rats is indicative of a slow increase in the number of hepatic nuclei rather than the cellular turnover of liver parenchyma.