[The karyometric characteristics of rat lung tissue during prenatal development].

The embryonic histogenesis of tissues of mesenchymal and epithelial origin was studied in the lungs of 150 embryos of the Albino rat (from 10 to 21 days of development) by methods of morphometry. Two phases in the dynamics of the nucleus form factor were established. The first phase (10-14 days) coincides with processes of programming and determination of the cells and is completed by a separation of the muscular, connective and cartilaginous tissues from the common mesenchymal germ. The second phase (16-21 days) is characterized by the divergent development of mesenchymal derivatives and demonstrates processes of cytodifferentiation and specialization of the cells. The appearance of heterogeneity of the cell forms leads to a growth of entropy of tissue anlagen. The restriction of the entropy is achieved by the integration of structures resulting from the formation of the system of correlation connections. Their amount first grows, and when specialization begins it becomes less.