[Use of the method of nucleus sedimentation fractionation for studying the dynamics of cell populations in the regenerating liver].

In different periods after partial hepatectomy (0, 11, 18, 24, 48 and 72 hours) isolated liver cell nuclei were separated according to their sizes using free sedimentation at 1 g in the exponential 0.1-1.0 M concentration gradient of sucrose at 4 degrees C. A sedimentogram of the intact liver cell nuclei displays three peaks corresponding to the nuclei of stromal cells, and diploid and tetraploid nuclei of hepatocytes. At 18 and 24 hours after the operation, but not at 0 or 11 hours, a curve of 3H-thymidine incorporation is represented by three maxima suggesting the influx of hepatocytes of different ploidy in the S-period. Then, 48 and 72 hours after the partial hepatectomy two additional peaks appear corresponding to 8- and 16-ploid nuclei, and a decrease in the portion of diploid nuclei is seen up to the full absence of the corresponding peak. Thus, the method of sedimentation at unit gravity of isolated nuclei using radioisotope labeling allows to obtain the information on the structure of the heterogeneous proliferating cell population.