[Mitotic activity of the endothelium of different-diameter blood microvessels in the mesentery of Wistar rats].

The technique of intravascular autoradiography of 3H-thymidine labeled nuclei of microvessels endothelia was developed. The density difference of labeled cells in microvascular bed of mesentery was estimated. The maximal density of labelled nuclei was found in pre- and postcapillary vessels, and minimal--in capillaries and large arteries and veins of mesenteric bed. The number of labeled nuclei per vessel was found to be relatively constant. The density of labeled cells in 4-months old rats is less than that in 3 weeks-old ones.