title: Morphological evidence for increased uterine vascular permeability at the time of embryonic attachment in the pig.
abstract: The morphology of subepithelial capillaries was studied in the endometrium of cyclic and pregnant gilts between Days 10 and 19 after estrus to determine whether evidence of increased vascular permeability accompanied embryonic attachment. No differences in the structure of the vessels were observed between Day 10 of the cycle and Day 10 of gestation, but striking regional modification had occurred by Day 13 of pregnancy. The portion of the capillary wall that was most proximal to the uterine epithelium was most attenuated and contained fenestrated segments, and caveolae had accumulated within the thicker distal face. As attachment progressed to Day 19 of pregnancy, thin fenestrated regions were even more extensive and the subepithelial capillaries were located in closer proximity to the uterine epithelium. In addition, modification of the basal lamina resulted in a discontinuous, thickened and multilayered appearance. These findings indicate a temporal association between morphological evidence of increased uterine vascular permeability and a close physical association between the uterine mucosa and trophoblast of elongated porcine blastocysts.
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Ontario, Canada.
authors.forename: J L
authors.initials: JL
authors.lastname: Keys
authors.forename: G J
authors.initials: GJ
authors.lastname: King
mesh_terms: D000818:Animals; D002199:Capillary Permeability; D010064:Embryo Implantation; D004848:Epithelium / Q000648:ultrastructure; D004971:Estrus; D005260:Female; D008854:Microscopy, Electron; D011247:Pregnancy; D013552:Swine; D014599:Uterus / Q000098:blood supply* / Q000648:ultrastructure