[Comparative study of the epithelium and mesenchyme of the rat small intestine during embryogenesis. I. Mitotic activity and nuclear volume].

The light optic investigation had been performed in rat embryos at the age of 10-20 days to study a successive formation of the small intestine wall and correlations between changes occurring in the nuclear volume and mitotic activity in its epithelium and mesenchyme. According to the ectodermal and mesodermal structures and to the changes in the nuclear volume and to the number of mitoses, it is possible to distinguish three periods. Certain correlations have been revealed between the nuclear volume and mitotic activity, which are of various significance during prespecific and specific differentiation