title: Progesterone supplementation extends uterine receptivity for blastocyst implantation in mice.
abstract: We previously showed that blastocyst can initiate implantation beyond the normal 'window' of uterine receptivity on day 5 of pregnancy and pseudopregnancy (PSP) in mice. In this study, we investigated whether uterine receptivity for blastocyst implantation can be further extended on day 6 of PSP and the role of progesterone (P(4)) on this event. Embryo transfers, experimentally induced decidualization, in situ hybridization and [(3)H]thymidine incorporation were performed. Blastocysts initiate attachment reaction within 48 h when transferred on day 5, but not on day 6 of PSP. Likewise, decidualization reaction occurred on days 4 and 5 of PSP, but completely failed on day 6. However, P(4) supplementation partially retains uterine receptivity for blastocyst implantation and decidualization on day 6 of PSP. In addition, certain indicators of uterine receptivity, such as cell proliferation profile and expression patterns of implantation-related genes were similarly observed on days 4 and 5 of PSP, but not on day 6. Consistent with embryo transfer and decidualization, exogenous administration of P(4) partially restores these indicators on day 6 of PSP. We concluded that critical physiological changes occur between days 4 and 5 of PSP, leading to uterine non-receptivity on day 6, but P(4) is able to extend the uterine receptivity through day 6.
authors.affiliation: Pathology and Immunology, Obstetrics and Gynecology, Washington University School of Medicine, 4566 Scott Avenue, St Louis, Missouri 63110, USA.
authors.forename: Haengseok
authors.initials: H
authors.lastname: Song
authors.forename: Kyuyong
authors.initials: K
authors.lastname: Han
authors.forename: Hyunjung
authors.initials: H
authors.lastname: Lim
mesh_terms: D000818:Animals; D001345:Autoradiography; D001755:Blastocyst / Q000502:physiology*; D049109:Cell Proliferation; D003656:Decidua / Q000502:physiology; D010064:Embryo Implantation / Q000235:genetics / Q000502:physiology*; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D015870:Gene Expression; D005865:Gestational Age; D017403:In Situ Hybridization; D053605:Leukemia Inhibitory Factor / Q000235:genetics; D051379:Mice; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology*; D011555:Pseudopregnancy / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D014599:Uterus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
chemical_list: D053605:Leukemia Inhibitory Factor; D012333:RNA, Messenger; D011374:Progesterone