DNA synthesis in the preimplantation mouse embryo

摘要: Strain PO preimplantation embryos were labelled with [ 3 H]thymidine. The incorporation of the label was studied by autoradiography air-dried and serially sectioned embryos. DNA amounts measured a microdensitometer. following observations made at 5- to 16-cell stages. All nuclei contained 2 C –4 all could eventually synthesize DNA. However, after short labelling intervals, unlabelled found 2C AC We concluded that both G 1 phases cell cycle present this time. Embryos in which S phase 4th 5th cycles post fertilization overlapped. In 12- 15-cell inside cells it produced one first four 8-cell-stage blastomeres divide. 9- 256-cell had significantly higher index than outside number increased faster during development. dividing cells. Blastocysts developed vivo or vitro greater 4 development excess does not depend on maternal environment. These exposures radioactivity. likely they becoming polyploid.