Effects of 3H-thymidine on preimplantation mouse embryos in vitro.
The effect of 3H-thymidine on in vitro development of preimplantation mouse embryos was studied. Two-cell and 4-8-cell embryos from B6CBA/F1 mice were continuously exposed to 3H-thymidine in medium containing 3H-thymidine in concentrations ranging from 10-500 nCi/ml. The effect of the radioactive precursor on embryo development to the blastocyst stage was studied by morphological observation, counting the blastocyst cell number and measuring 3H-thymidine incorporation. The continuous presence of 3H-thymidine significantly inhibited development of 2-cell and 4-8-cell embryos to the blastocyst stage. Embryos cultured from the 2-cell stage were more sensitive to 3H-thymidine than those exposed from the 4-8-cell stage. Even in morphologically normal blastocysts the cell number was significantly reduced. A 2 hr pulse of 100 nCi/ml 3H-thymidine at the blastocyst stage, did not affect the blastocyst formation or the blastocyst cell number and the amount of incorporated 3H-thymidine was sufficient to provide a reliable quantitation of DNA synthesis during the culture of preimplantation embryos in vitro. Continuous incubation with 3H-thymidine in order to measure DNA synthesis of preimplantation mouse embryos should be avoided when DNA synthesis is used as a means of evaluating toxic effect of an agent. Adverse radiation effects by 3H-thymidine on preimplantation mouse embryos during toxicity testing can be avoided by pulse labelling.
Department of Microbiology, Dental Faculty, University of Oslo, Norway.
W M
WM
Olsen
R
R
Storeng
D000818:Animals; D001755:Blastocyst / Q000187:drug effects*; D004247:DNA / Q000096:biosynthesis; D005260:Female; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D011247:Pregnancy; D013936:Thymidine / Q000494:pharmacology*
D004247:DNA; D013936:Thymidine