Summary. A single oral administration of centchroman (1·25 mg/kg) to adult female rats within 24 h of mating induced slight acceleration in the rate of transport of embryos through the oviducts. The compound did not seem to produce any deleterious effect on preimplantation embryonic development since well organized and apparently normal embryos were collected from the genital tract up to Day 12 of pregnancy. The recovery rate of embryos from centchroman-treated rats was, however, significantly reduced after Day 4 of pregnancy. There was some stimulation in the rate of cleavage of embryos and morula to blastocyst transformation, but retardation in the shedding of the zona pellucida. The rate of blastocyst formation was not altered when 6–8-cell embryos collected from the oviducts of control rats were transferred to the uteri of control or centchroman-treated females. A delay in zona shedding was observed in the centchroman-treated recipients.
M. M. Singh, V. Bhalla, V. Wadhwa, and V. P. Kamboj
M. M. Singh, V. Wadhwa, N. Sethi, and V. P. Kamboj
Summary. 'Tube-locked' morulae and blastocysts were recovered from the ampulla of the oviduct of centchroman-treated mice between Days 4 and 12 post coitum and transferred to the uteri of pseudopregnant female mice. Pregnancy and implantation rates were lower and the post-implantation resorption rate was higher in the treated than in the control group. There was little difference in the pregnancy or implantation rates between embryos recovered on Days 4 or 12 post coitum, but the resorption rate increased with increasing duration of embryos in the oviducts and was 100% for the Day-12 embryos. The resorption rate was similar even when these embryos were transferred to the sterile uterine horn of unilaterally pregnant mice. Centchroman did not produce any deleterious effect on embryos which survived until Day 19 of pregnancy in foster mothers. The average fetal weight was also comparable to those of control fetuses.