title: Embryo-dependent induction of embryo receptivity in the mouse endometrium.
abstract: The effect of intraoviductal embryos on endometrial receptivity was studied by intraendometrial and intrauterine embryo transfer. Five-week-old female ICR mice were mated after superovulation; a vaginal plug confirmed day 1 of pregnancy. On day 4 (90 h after hCG injection), blastocysts were collected and transferred to pseudopregnant female mice and to recipient mice in which the uterotubal junction had been ligated bilaterally on day 1 of pregnancy. Three embryos per uterine horn, a total of six embryos per recipient mouse at days 1-6, were transferred to the endometrium or uterine cavity and implantation and pregnancy rates were calculated. The implantation rate for intraendometrial embryo transfer to recipients of days 3, 5 and 6 was significantly higher for uterotubal junction-ligated mice (72.2, 20.8 and 9.7%, respectively) than for pseudopregnant mice (55.0, 8.3 and 0.0%, respectively). The implantation rate for intrauterine embryo transfer to recipients at days 2, 5 and 6 was significantly higher for uterotubal junction-ligated mice (11.1, 25.0 and 8.3%, respectively) than for pseudopregnant mice (0.0, 3.3 and 0.0%, respectively). Uterotubal junction-ligated mice achieved implantation and bore neonates by intrauterine embryo transfer on days 2 and 6, whereas no implantation was achieved in pseudopregnant mice. The difference in implantation rate could not be explained by a difference in progesterone concentration between the groups. The distribution of proliferating cells in the endometrium was also studied immunohistochemically by use of anti-proliferating cell nuclear antigen (PCNA) antibody in the recipient mice. PCNA-positive cells were more abundant in uterotubal junction-ligated mice and demonstrated a marked extension from the epithelium to the stroma over time, in contrast to those in pseudopregnant mice. These findings indicate that an intraoviductal embryo exerts a biological effect by sending a signal to the endometrial epithelium and stroma, thus facilitating endometrial receptivity to the embryo and improving the rate of implantation.
authors.affiliation: Department of Obstetrics and Gynecology, Shiga University of Medical Science, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Wakuda
authors.forename: K
authors.initials: K
authors.lastname: Takakura
authors.forename: K
authors.initials: K
authors.lastname: Nakanishi
authors.forename: N
authors.initials: N
authors.lastname: Kita
authors.forename: H
authors.initials: H
authors.lastname: Shi
authors.forename: M
authors.initials: M
authors.lastname: Hirose
authors.forename: Y
authors.initials: Y
authors.lastname: Noda
mesh_terms: D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D010064:Embryo Implantation / Q000502:physiology*; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000502:physiology*; D004717:Endometrium / Q000502:physiology*; D005260:Female; D007150:Immunohistochemistry; D051379:Mice; D008813:Mice, Inbred ICR; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D011555:Pseudopregnancy; D018709:Statistics, Nonparametric
chemical_list: D006063:Chorionic Gonadotropin; D018809:Proliferating Cell Nuclear Antigen; D011374:Progesterone