title: Study of the murine allantois by allantoic explants.
abstract: The murine allantois will become the umbilical artery and vein of the chorioallantoic placenta. In previous studies, growth and differentiation of the allantois had been elucidated in whole embryos. In this study, the extent to which explanted allantoises grow and differentiate outside of the conceptus was investigated. The explant model was then used to elucidate cell and growth factor requirements in allantoic development. Early headfold-stage murine allantoises were explanted directly onto tissue culture plastic or suspended in test tubes. Explanted allantoises vascularized with distal-to-proximal polarity, they exhibited many of the same signaling factors used by the vitelline and cardiovascular systems, and they contained at least three cell types whose identity, gene expression profiles, topographical associations, and behavior resembled those of intact allantoises. DiI labeling further revealed that isolated allantoises grew and vascularized in the absence of significant cell mingling, thereby supporting a model of mesodermal differentiation in the allantois that is position- and possibly age-dependent. Manipulation of allantoic explants by varying growth media demonstrated that the allantoic endothelial cell lineage, like that of other embryonic vasculatures, is responsive to VEGF(164). Although VEGF(164) was required for both survival and proliferation of allantoic angioblasts, it was not sufficient to induce appropriate epithelialization of these cells. Rather, other VEGF isoforms and/or the outer sheath of mesothelium, whose maintenance did not appear to be dependent upon endothelium, may also play important roles. On the basis of these findings, we propose murine allantoic explants as a new tool for shedding light not only on allantoic development, but for elucidating universal mechanisms of blood vessel formation, including vascular supporting cells, either in the intact organism or in existing in vitro systems.
authors.affiliation: Department of Anatomy, University of Wisconsin--Madison Medical School, 1300 University Avenue, Madison, Wisconsin 53706, USA. kdowns@facstaff.wisc.edu
authors.forename: K M
authors.initials: KM
authors.lastname: Downs
authors.forename: R
authors.initials: R
authors.lastname: Temkin
authors.forename: S
authors.initials: S
authors.lastname: Gifford
authors.forename: J
authors.initials: J
authors.lastname: McHugh
mesh_terms: D000482:Allantois / Q000098:blood supply / Q000166:cytology / Q000187:drug effects / Q000196:embryology*; D000818:Animals; D001808:Blood Vessels / Q000166:cytology / Q000187:drug effects / Q000196:embryology; D002454:Cell Differentiation; D002455:Cell Division; D002465:Cell Movement; D002470:Cell Survival; D003470:Culture Media; D046508:Culture Techniques; D016228:Endothelial Growth Factors / Q000494:pharmacology; D004727:Endothelium / Q000196:embryology; D004848:Epithelium / Q000196:embryology; D005260:Female; D018507:Gene Expression Regulation, Developmental; D007763:Lac Operon; D008222:Lymphokines / Q000494:pharmacology; D008648:Mesoderm / Q000166:cytology; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008822:Mice, Transgenic; D011247:Pregnancy; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: D003470:Culture Media; D016228:Endothelial Growth Factors; D008222:Lymphokines; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors