Endometrial Surface and Secretory Alterations Associated with Embryonic Mortality in Gilts Administered Estradiol Valerate on Days 9 and 10 of Gestation1

Abstract

Administration of estrogen to gilts on Days 9 and 10 of pregnancy results in total embryonic loss by Day 18. The present study examined changes in the uterine endometrial surface and secretion during conceptus attachment in control and estrogen-treated (Days 9 and 10) pregnant gilts. Gilts were unilaterally hysterectomized on either Days 12 and 14 or Days 16 and 18 of gestation. Uterine horns were flushed with saline and conceptuses were evaluated. Intact conceptuses were recovered from all control gilts, whereas estrogen-treated gilts contained normal intact conceptuses only on Day 12 of gestation. Antiviral activity, which reflects conceptus viability, was reduced (p less than 0.01) in uterine flushings after Day 14 in estrogen-treated gilts. Culture of endometrial explants with [3H]glucosamine revealed several glycoproteins that are synthesized during the period of conceptus attachment; however, no difference in glycoprotein synthesis between treatment groups was detected by analysis with two-dimensional PAGE and fluorography. Analyses of the uterine epithelium by scanning and transmission electron microscopy demonstrated that estrogen administration caused an alteration in the uterine surface, a thinning of the uterine epithelial glycocalyx, and a reduction of cationic ferritin binding to the microvilli of the uterine epithelium. Results indicate that conceptus mortality after early administration of estrogen is associated with alterations in the uterine endometrial surface during the period of conceptus attachment in the pig.

Implantation and Establishment of Pregnancy in the Pig

“…Administration of estrogen prior to the window of receptivity for conceptus elongation and attachment results in fragmentation and degeneration of the conceptuses between days 14 and 18 of pregnancy (Gries et al 1989 ). Conceptus degeneration results from a breakdown in the surface glycocalyx of uterine LE (Blair et al 1991 ), alterations in uterine protein secretion, and aberrant endometrial transcriptional activity during the period of conceptus attachment (Ashworth et al 2012b ). Thus, the utilization of estrogen as one of the major signals to maintain CL throughout pregnancy in the pig makes the pig susceptible to the disruptive effects of environmental estrogens during early pregnancy.…”

Characterization of glycoconjugates in the endometrium of the miniature pig during different reproductive periods

“…Administration of exogenous hormones could alter the characterization of glycoconjugates in the endometrium and result in the degeneration of conceptuses (Blair et al, 1991;Kramber, 1992 …”

Characteristics of the uterine luminal surface epithelium at preovulatory and preimplantation stages in the marmoset monkey

“…Perhaps the state of the plasma membrane and associated glycocalyx of each uterine epithelial cell reflects the transient metabolic and synthetic activity of the cell, especially related to glycolysis. Preference of CF staining for MV and inter-MV membranes has also been described previously in the rat (Hewitt et al, 1979) and gilt (Blair et al, 1991). How such localized arrangement of anionic sites influences blastocyst apposition is not known.…”