title: Oct4 protein remains in trophectoderm until late stages of mouse blastocyst development.
abstract: Oct-4, the marker of pluripotent cells, is crucial for murine preimplantation development. During the formation of the blastocyst Oct-4 is downregulated in the trophectoderm (TE) and its expression becomes restricted to the inner cell mass (ICM). In order to determine the exact timing of the disappearance of Oct-4 protein from TE we analyzed the localization and level of Oct-4 at different stages of blastocyst development. The presence of Oct-4 protein was determined by immunohistochemistry using confocal microscopy. We found that the downregulation of Oct-4 protein in TE of mouse blastocysts progresses gradually during development, and Oct-4 protein persists in some of the TE cells at least until the expanded blastocyst (120-140 cells) stage. Our findings indicate that the switching-off of the Oct-4 expression is not necessary for the trophectoderm formation. The complete elimination of Oct-4 protein from TE occurs at the period of blastocyst implantation, when lack of Oct-4 is required for the proper functioning of the trophectoderm.
authors.affiliation: Department of Embryology, Institute of Zoology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland. kasiasz@biol.uw.edu.pl
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Szczepańska
authors.forename: Lukasz
authors.initials: L
authors.lastname: Stańczuk
authors.forename: Marek
authors.initials: M
authors.lastname: Maleszewski
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D015536:Down-Regulation; D004475:Ectoderm / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D051379:Mice; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism*
chemical_list: D050814:Octamer Transcription Factor-3; C494174:Pou5f1 protein, mouse