Increased litter size in the rat x-irradiated during the estrous cycle before mating

Does x-radiation of the preconceptional mammalian ovum lead to sterility and/or congenital anomalies?

Sexually mature CF1 female mice were x-radiated with 10 to 500 R prior to mating with normal males of the same strain, and no exposure rendered the mice sterile immediately; estrous was not altered, so that normal matings occurred; the litter size of females exposed to the 500-R dose was reduced, possibly due to induction of dominant lethal genes. The second and third meiotic maturations following x-radiation gave rise to fertilizable ova which resulted in offspring that did not show any increase in the incidence of congenital anomalies. With increasing levels of exposure to x-rays, there was a decrease in the reproductive live-span. If the interval between x-radiation and mating was lengthened to 60 days, none of those exposed to 300 R or more was fertile; those exposed to 100 R showed variable fertility, evidenced by reduced litter sizes, but there were no anomalies. None of the offspring of the x-radiated females showed a significant weight loss, even to 2 months of age. Thus, when ova were x-rayed before fertilization with normal sperm, normal fertilization occurred and normal offspring were produced from at least the first three successive estrous cycles; after that, various degrees of sterility were evident, depending upon the dose level of the original exposure. Since resorptions (but not anomalies) were increased with the higher doses, dominant lethal and recessive mutatuions may have been obscured by the normal alleles of the unirradiated male mates. The ovarian ovum could not readily be sterilized by x-rays, nor could it be so damaged as to cause congenital anomalies. Nevertheless, one must be aware that all x-rayed ova may carry recessive mutatuions which might be phenotypically evident if they are on the female sex (X) chromosome, unmasked by an allelomorph on the male (Y) chromosome, or might even surface in future generations, if chance combines them with similar genes.

Prevention of radiation-induced creatinuria by insulin

Insulin completely suppressed creatinuria in rats x-irradiated with an absorbed dose of 500 rads. The hormone may exert this effect either by restoring or maintaining the ability of irradiated muscle to take up creatine from the extra-cellular fluid at a normal rate, or possibly by influencing the synthesis or breakdown of phosphorylcreatine.