[Changes in the amount and synthesis of DNA in the nuclei of large decidual cells in rats during their differentiation].

Using cytophotometry of the Feulgen-stained nuclei, the quantity of DNA was measured in the nuclei of rat's large decidua cells (LDC) on tissue sections of the antimesometrial region within days 7-13 of gestation. The quantity of nuclear DNA was expressed in units of ploidy, the haploid DNA standard being the quantity of DNA in rat's spermatid nucleus. On different days of gestation, the nuclear DNA was seen to vary in cells located in different zones of decidua. The maximum DNA content was found in the LDC located on days 9-12 of gestation somewhat in the middle of the decidua thickness. On day 11, the quantity of nuclear DNA in these cells reached in average, 22c. The quantity of DNA in the nuclei of the least differentiated LDC located on the periphery of decidua never exceeded 4.9c, whereas that in the nuclei of the most differentiated LDC, located close to the embryo, varied from 2.9c to 9.3c. On days 10 and 11 of rat's false gestation, the maximum DNA contents in the nuclei were registered in the LDC located in the middle of the decidua thickness. 3H-thymidine incorporation into the nuclei of the most differentiated LDC located nearest to the embryo stopped starting from day 10 of gestation. Phenomena of lesser quantities of nuclear DNA in most differentiated LDC, compared to that in LDC in the previous steps of differentiation, are discussed.