PREIMPLANTATION EMBRYONIC LOSS INDUCED BY TRIBUTYLTIN CHLORIDE IN RATS

The effect of tributyltin chloride (TBTCl) administered during early p regnancy on pregnancy maintenance was evaluated in rats. Inseminated f emales were orally administered TBTCl at a dose of 0, 8.1, 12.2 or 16. 3 mg/kg on day 0 through day 7 of pregnancy. Females were sacrificed o n day 20 of pregnancy and pregnancy outcome was determined. Pregnancy failure, which was evidenced by absence of implantation sites, was fou nd in 0 of the 10, in 2 of the 11, in 10 of the 14 and in 10 of the 13 females at 0, 8.1, 12.2 and 16.3 mg/kg, respectively. The rate of pre gnancy failure was significantly higher in the 12.2 and 16.3 mg/kg gro ups than that in the control group. In females with successful pregnan cy, the numbers of corpora lutea, implantations and post-implantation loss per litter were comparable across all groups. No increase in the incidence of malformed fetuses was found in any TBTCl-treated groups. Thus it appears that TBTCl causes pregnancy failure after administrati on during very early pregnancy.