Effect of postcoital oestradiol treatment upon transport, growth, differentiation and viability of preimplantation mouse embryos
Roblero, L.S.; Moscoso, H.E.; Riffo, M.
Archivos de Biologia y Medicina Experimentales 16(1): 55-59
1983
ISSN/ISBN: 0004-0533 PMID: 6680982 Document Number: 201554
The relative contribution of ovum transport anomalies and alterations of various developmental parameters upon the contraceptive effect of postcoital estrogen treatment was studied in mice. Females received a single s.c. injection from 0.001-100 .mu.g of estradiol or vehicle on day 1 of pregnancy and were sacrificed 28, 52 or 76 h after treatment to determine the location and development of embryos in the genital tract, or on day 12 of pregnancy to assess the number of viable implanted embryos. Preimplantation embryos were classified according to developmental parameters into normal, retarded or arrested. Pregnancy was completely suppressed by 10 and 100 .mu.g of estradiol. A partial and dose related block of pregnancy was observed with 0.01-1 .mu.g of estradiol. Treatment with these doses was associated with delayed oviductal transport, decreased cleavage rate, inhibition of blastulation and arrested development. The number of implanted embryos recorded on day 12 coincided with the number of normal embryos observed at 76 h, regardless of their location and numbers of cells. Statistically significant but minor decreases in the cleavage rate and transitory oviductal retention caused by estradiol neither prevented implantation nor affected subsequent viability of mouse embryos. The inhibition of pregnancy that follows postcoital administration of estradiol is associated with a variety of effects upon embryo transport and preimplantation development, which appear in different combinations with each dose and contribute unequally to its interceptive effect.