Effect of light schedule inversion on mitotic cycle parameters in the esophageal epithelium of mice

: Parameters of the cell mitotic cycle (MC) in the esophageal epithelium of mice were studied 5, 10 and 17 days after inverting the light schedule (light from 8 a. m. to 8 p. m. in the control group, L : D = 12:12, and light from 8 p. m. to 8 a. m. in the experimental one., L : D = 12:12). The duration of different MC periods is similar in the control and experimental animals at varying time after inversion of the light schedule: G2min- 1.0-2.0 h, G2 + 1/2M = 2.0 -2.7 h, S = 7.1-7.7 h, G1 + 1/2M = 14.0-15.5 h. The total MC duration is 24-25 h. The pattern of the labeled mitotic curves after inversion only slightly differs from the control. This is evidence of stability of MC cell kinetics after inversion of the light schedule. The intracyclic regulatory mechanisms appear not to be affected essentially by this inversion.