Can the mammalian embryo be killed by X-irradiation?

Journal Article · Sat Dec 01 04:00:00 EST 1962 · Journal of Experimental Zoology

DOI:https://doi.org/10.1002/jez.1401510304· OSTI ID:4679845

Rugh, Roberts; Wohlfromm, Marlis

In CF1 mice, 1181 pregnancies and 11,825 implantations were used to determine the dose of x rays that would kill 50% of their embryos studied from the 1st to 17th days of gestation. The extrapolated LD₅₀ values varied from 100 r at fertilization to 800 r on the 18th day. Embryos x irradiated from 0.0 to 9.0 days were found to be relatively more sensitive than those x irradiated during the second half of pregnancy. The greatest radiosensitivity occurred at 0.0, vulnerable. Embryos at 6 days were relatively resistant. The periods of maximum radiosensitivity occurred during syngamy, the morula stage, and neurogenesis. The embryonic period of greatest resistance was at implantation and gastrulation. The implantation number was not appreciably affected by x rays except at 0.5 days when the litter number average dropped from the control level of 9.86 to 7.89 after an exposure of 250 r. This probably indicated high mortality in the very early stages of cleavage, leaving no implantation residue. The data on survival, therefore, relate to implantation numbers so that the extrapolated LD₅₀ for the early (0.5-day) embryo is probably much too high. Irradiated early embryos rarely survive to die as fetuses, but die quickly to leave a resorption mass that persists. Embryos rarely die as fetuses except when x irradiated after day 7.0. Congenital anomalies resulted from exposure at almost every gestation age. The most consistent and frequent result of embryonic or fetal x irradiation was stunting. Except during the period of 10 to 13 days, when there were many accompanying anomalies, there appeared to be little alteration in the topography of the stunted fetuses. It was concluded that no value can be ascribed to theLD₅₀ for the embryo because there is no such static entity. (TCO)

• Research Organization: Columbia Univ., New York
• Sponsoring Organization: USDOE
• NSA Number: NSA-17-024944
• OSTI ID: 4679845
• Journal Information: Journal of Experimental Zoology, Journal Name: Journal of Experimental Zoology Journal Issue: 3 Vol. 151; ISSN 0022-104X
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

AGE
BIOLOGY AND MEDICINE
EMBRYOS
FETUSES
LETHAL DOSE
MALFORMATIONS
MEASURED VALUES
MICE
PREGNANCY
RADIATION INJURIES
RADIOSENSITIVITY
X RADIATION