[Nucleoli of mesothelial cells during regeneration after injuries inflicted at different times of the day].

Quantitative changes in nucleoli of the mesothelial cells of the rabbit parietal peritoneum have been studied under regeneration when trauma is performed at 8--10 or at 20--22 o'clock. The animals are killed every 3 h after the operation, for 5 days. The nucleoli are studied continuously along 12.8 mm from the edge of the defect in film preparations. Under conditions of posttraumatic regeneration in the mesothelium the number of cells containing 2--3 nucleoli increases. It is connected with the process of synthesis activation which has a wave-like character in time and space. Dynamics of changes in the number of the nucleoli depends on the time when the operation is performed. The operation performed in the morning provokes more intensive and rhythmical reaction. It corresponds to the dynamics of mitotic activity which is also subjected to greater effects of the circadian mechanisms after morning performance of the operation.