Effect of 2,4,6,Triamino-“S”-Triazine (TR),2,4,6 “Tris” (Ethyleneimino)-“S”-Triazine (TEM) and N,N′,N″-Triethylenephosphoramide (TEPA) on Rat Litter in Utero. ∗

Summary

1. The effect of TR, TEM and TEPA on rat fetus and litter in utero was studied with 2 doses of the 5 LD₅₀ on 4th and 5th, or 7th and 8th, or 11th and 12th days of gestation. 2. TR had no effect on the rat litter and can be regarded as a control series to TEM. 3. TEM had its maximum effect at the time of implantation, but failed to destroy the entire litters. An increase in dosage from .3 mg/kg to .5 mg/kg given at the time of implantation led to 100% litter destruction. 4. Progesterone administration protected 40% of the fetuses against otherwise lethal doses of TEM. 5. Rats treated with TEM displayed uniformly smaller placentas than normal. 6. TEM in combination with AZS given on the 15th and 16th days of gestation led to much stunting of the fetuses, to 32% of fetal death, but in no instance to complete litter destruction. 7. Freshly prepared TEPA destroyed all litters when given on the 7th and 8th, or 11th and 12th days of gestation. 8. The malformations observed with TEM and TEPA consisted of cranial defects and abnormalities of facial structures. 9. TEM and TEPA in doses used affected adversely the bone marrow and lymphoid system of the mother animals.