Effect of O-Diazo Acetyl-L-Serine on Rat Litter. ∗

Summary

1. The observation that AZS affects the rat fetus in utero is confirmed and greatly extended. 2. AZS acts on the fetus directly—and not on the ovary, placenta or pituitary. 3. AZS efficiently destroys the entire litter of rats in doses of: (a) 5 mg/kg at the time following implantation (7th and 8th days of gestation); (b) 10 mg/kg at midterm (11th and 12th days of gestation); without affecting the mothers adversely. 4. This drug effect is sharply limited in time. 5. Combination of 6MP and AZS was effective in litter destruction in smaller doses than either compound alone. 6. Neither progesterone nor adenine protected the litter against AZS. 7. AZS given before mating did not delay it, nor did it affect the subsequent litter. 8. Rats aborted 4 and 5 consecutive times with AZS showed no accumulative toxicity nor impairment of their fertility. 9. Litters raised from rats aborted 4 or 5 times were normal in all respects and produced normal litters.