Pregnant Swiss albino mice were given on day 11.25 post conception a priming intraperitoneal (i.p.) injection of tritiated water at the activity levels 37, 74 or 185 kBq/ml body water, in the absence (control) or presence (experimental) of 2-mercaptopropionylglycine (MPG), 20 mg/kg body weight, given intraperitoneally 30 minutes before the tritium administration. The females were subsequently maintained on tritiated drinking water until term, at the above activity level, in the control series. The animals of the experimental series received in addition a daily i.p. injection of MPG at the same time of the day, until term. A third series received a daily injection of the drug, but no tritium, at the same dose rate. None of the females from the control series had parturition, and a gradual decline in their weight was recorded, exhibiting resorption. Treatment with MPG led to an obvious increase in embryonic survival in all groups, and even in the 185 kBq group two-thirds of the females had parturition.

Pregnant Swiss albino mice were exposed at gestation days 141/4, 161/4 and 181/4 to 1.5 Gy gamma radiation from 60Co in the presence or absence of 2-mercaptopropionylglycine (MPG). Liver was taken from the litters born to these mothers at different post-partum intervals. The maximum sensitivity was found in 4-week-old animals irradiated at gestation day 141/4. In the MPG treated groups, the number of total cells was higher than in the controls but less than in normals. The increase in pyknotic nuclei and necrotic and binucleate cells was significantly lowered by MPG.

Radiosensitivity of the primordial germ cells and its protection was estimated from the surviving number of spermatids in the 6 weeks old testes of control and MPG-pretreated mice after intrauterine exposure to 0.5, 1.5 and 2.5 Gy60Co gamma rays during fetal growth period. Radiosensitivity of fetal testes was found to increase with the advent of embryonic age. Quantitatively, significant protection in testes weight and spermatids count was registered in the MPG-pretreated animals at all the 3 dose levels studied.

Pregnant Swiss albino mice were whole-body exposed to 250, 150 and 50 R gamma-radiation from 60Co in the presence or absence of 2-mercaptopropionylglycine during selective organogenesis and fetal growth periods (days 11.25 and 14.25, 16.25 and 18.25 after conception, respectively). Both the protected and nonprotected pregnant females of 11.25-day gestation showed complete resorption of embryos irradiated with 250 R. With 150 R, in absence of the drug, 11.25-day gestating females showed partial resorption (76.10%). The percentage of parturition improved in the drug-treated females. Nonprotected females irradiated with 50 R showed slight resorption, while drug-treated females had normal parturition. Females irradiated during the fetal growth period showed no resorption. Also, no significant alteration in litter size and sex ratio of the newborn animals was noticed when irradiated during this period, both in the control and the experimental groups. Mortality of the young was higher in nonprotected animals as compared to the protected ones.

Pregnant Swiss albino mice at different fetal growth periods were exposed to 150 R gamma rays in the presence or absence of 2-mercaptopropionylglycine (MPG), a SH radioprotector. The weights of litters born to these mothers were recorded at different post-partum intervals. There was an initial weight loss at 1 week after birth followed by a second weight loss after 4 weeks in the unprotected control males, whereas females showed continuous gains in weight from initial loss at 1 week. In the MPG-treated groups, the pattern of weight changes remained the same, but the loss was significantly less than in the controls and the second weight loss in the case of males was not obvious.

2-Mercaptopropionylglycine administered during fetal growth period, protected significantly young mice against loss of body weight during postnatal development induced by 50 R gamma irradiation.

Gamma radiation (150 R) was given in utero at different gestation days, namely 14 1/4, 16 1/4 and 18 1/4, to Swiss albino mice, pretreated with either MPG or double distilled water. Erythrocytes from peripheral blood were counted in young ones at 1, 2, 4 and 6 weeks after birth. The result indicated that erythrocyte count in the MPG treated group was significantly higher than in the unprotected ones at 1 and 2 weeks of postnatal development, after which the values of both control and experimental groups were comparable to that of the normal.