title: Immunohistochemical localization of cytokeratins in the junctional region of ectoderm and endoderm.
abstract: Although tridermic species have two junctional regions of ectoderm and endoderm between their epidermis and digestive tract, we actually know little about these particular boundaries. Cytokeratins are the major intermediate filaments of epithelial cells and show a high degree of tissue specificity. Therefore, to characterize the epithelial cells in the junctional region of ectoderm and endoderm, we immunohistochemically examined the localization of cytokeratins 5, 7/17, 14, 18, Sox17, and alpha-fetoprotein (AFP) in the oropharyngeal and anorectal regions during the mouse gastrulation process. At embryonic day (E) 9.5, cytokeratins 5, 7/17, 14, and 18 were detected in all epithelial cells of the oropharyngeal region. At E12.5, cytokeratin 5-positive cells were not observed in the middle area of the oral cavity; however, the immunoreactivity was strong in the anterior and posterior areas. The immunoreaction of cytokeratins 18 was seen only in the middle and posterior areas of the oral mucosa. Cytokeratins 7/17 and 14 were localized in all areas of the oropharyngeal region. Sox17 and AFP, which are endodermal markers, were detected in the middle and posterior areas of the oral mucosa, but not in the anterior area. Moreover, this same localization pattern of cytokeratins also existed in the anorectal region of the E12.5 embryo, suggesting that the localization of cytokeratins and endodermal markers might give an implication for the boundary between ectoderm and endoderm. These results also suggest that these cytokeratins are useful molecules for monitoring the epithelial cell differentiation in the junctional region of the germ layers.
authors.affiliation: Division in Anatomy and Developmental Biology, Department of Oral Biology, Research Center for Orofacial Hard Tissue Regeneration, Brain Korea 21 Project, Yonsei University College of Dentistry, Seoul, Republic of Korea.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Hosoya
authors.forename: Sungwook
authors.initials: S
authors.lastname: Kwak
authors.forename: Eun-Jung
authors.initials: EJ
authors.lastname: Kim
authors.forename: Declan Patrick
authors.initials: DP
authors.lastname: Lunny
authors.forename: E Birgitte
authors.initials: EB
authors.lastname: Lane
authors.forename: Sung-Won
authors.initials: SW
authors.lastname: Cho
authors.forename: Han-Sung
authors.initials: HS
authors.lastname: Jung
mesh_terms: D001003:Anal Canal / Q000166:cytology / Q000378:metabolism; D000818:Animals; D015415:Biomarkers; D002454:Cell Differentiation; D004475:Ectoderm / Q000166:cytology / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism*; D004707:Endoderm / Q000166:cytology / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005260:Female; D054262:Gastrulation; D007365:Intercellular Junctions / Q000378:metabolism*; D053547:Keratin-14 / Q000378:metabolism; D053538:Keratin-18 / Q000378:metabolism; D053555:Keratin-5 / Q000378:metabolism; D053552:Keratin-7 / Q000378:metabolism; D007633:Keratins / Q000378:metabolism*; D051379:Mice; D009960:Oropharynx / Q000166:cytology / Q000378:metabolism; D011247:Pregnancy; D012007:Rectum / Q000166:cytology / Q000378:metabolism
chemical_list: D015415:Biomarkers; D053547:Keratin-14; D053538:Keratin-18; D053555:Keratin-5; D053552:Keratin-7; D007633:Keratins