title: Radiosensitivity variation during the cell cycle in pronuclear mouse embryos in vitro.
abstract: The radiosensitivity of pronuclear mouse (B6D2 F2 X ICR) embyros has been measured in vitro as a function of time during the cell cycle. This was done by measuring the dose of X-rays (LD50) required to prevent development of 50% of the pronuclear embryos to the blastocyst stage in 5 days of culture. The LD50 was found to vary from 1 to 2 Gy during the period from G1 to the first cleavage. The cell cycle in the pronuclear embryo was analysed by [3H]thymidine autoradiography. Compared with earlier studies on two-cell mouse embryo radiosensitivity, the pronuclear embryos appear to be more sensitive to radiation than the two-cell embryos. If, however, one considers the radiation sensitivity on a blastomere basis, the pronuclear embryos are not different in their radiation sensitivity from the two-cell embryos. Thus, during the early cleavage stages of mice, radiosensitivity is mainly governed by the content of cells of various cell cycle ages in the embryo.
mesh_terms: D000818:Animals; D001757:Blastomeres / Q000528:radiation effects; D002453:Cell Cycle; D005260:Female; D066298:In Vitro Techniques; D007928:Lethal Dose 50; D051379:Mice; D011247:Pregnancy; D011270:Pregnancy, Animal; D011836:Radiation Tolerance; D013997:Time Factors; D015053:Zygote / Q000528:radiation effects*