title: Superficial implantation in pigs is associated with decreased numbers and redistribution of endometrial NK-cell populations.
abstract: OBJECTIVE
  We evaluated implantation-associated quantitative changes in endometrial and peripheral natural killer (NK)-cell populations of pigs.
  
  
  METHODS
  Natural killer cell populations were investigated in 10, 15, 20, 30 and 40 days pregnant and non-pregnant (NP) sows by flow cytometry, immunohistochemistry and morphometry.
  
  
  RESULTS
  The number of endometrial CD16(+) NK cells significantly declined at attachment phase of implantation and remained relatively low over the course of implantation. The CD16(+) NK cells in situ showed implantation-phase dependent density and localization. Prior to implantation, they substantially resided in the subepithelial stroma. As implantation advances, the density of NK cells into subepithelial stroma decreased while that of NK cells into glandular layer increased, suggesting implantation-induced re-location far from the attached conceptus. The number of CD56(+) lymphocytes was the greatest at pre-attachment phase of implantation, dropped at the time of attachment and increased up to end of early pregnancy period. The CD3(-) CD8(+) NK-cell number decreased significantly when the definitive placenta is established. No significant differences in the numbers of peripheral blood CD16(+), CD56(+) and CD3(-) CD8(+) NK cells between pregnant and NP animals as well as relative to the implantation phase were observed.
  
  
  CONCLUSIONS
  Superficial and adeciduate implantation of pigs is associated with decreased numbers of endometrial NK-cell populations and specific spatiotemporal profile of classical NK cells.
authors.affiliation: Department of Immunobiology of Reproduction, Institute of Biology and Immunology of Reproduction acad.K.Bratanov, Bulgarian Academy of Sciences, Sofia, Bulgaria. tanyadimova@yahoo.com
authors.forename: Tanya
authors.initials: T
authors.lastname: Dimova
authors.forename: Anastassia
authors.initials: A
authors.lastname: Mihaylova
authors.forename: Petia
authors.initials: P
authors.lastname: Spassova
authors.forename: Rayna
authors.initials: R
authors.lastname: Georgieva
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D010064:Embryo Implantation / Q000276:immunology*; D004717:Endometrium / Q000166:cytology* / Q000276:immunology*; D005260:Female; D017403:In Situ Hybridization; D007694:Killer Cells, Natural / Q000166:cytology* / Q000276:immunology; D018655:Lymphocyte Count; D011247:Pregnancy; D013552:Swine / Q000276:immunology*; D013997:Time Factors
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD