title: Placental apoptosis in normal human pregnancy.
abstract: OBJECTIVE
  The study aims were to conclusively demonstrate apoptosis in the human placenta and to quantify its incidence at different stages of pregnancy.
  
  
  METHODS
  Placental samples were obtained from 28 first-trimester pregnancies and 38 uncomplicated third-trimester pregnancies. Light microscopy, electron microscopy, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate marker nick end-labeling staining were used to identify apoptosis. Light microscopy was used to quantify its incidence.
  
  
  RESULTS
  Apoptosis has been conclusively demonstrated within placental tissue. Quantification of apoptosis (medians and interquartile ranges) was as follows: first trimester (n = 28), 0.07% of cells (0.05% to 0.14%); third trimester (n = 39), 0.14% of cells (0.09% to 0.20%). The incidence of apoptosis was significantly higher in the third trimester than in the first trimester (p < 0.01, Mann-Whitney U test).
  
  
  CONCLUSIONS
  Placental apoptosis increases significantly as pregnancy progresses, suggesting that it may play a role in the normal development and aging of the placenta.
authors.affiliation: University Department of Obstetrics and Gynaecology, University of Nottingham, City Hospital, United Kingdom.
authors.forename: S C
authors.initials: SC
authors.lastname: Smith
authors.forename: P N
authors.initials: PN
authors.lastname: Baker
authors.forename: E M
authors.initials: EM
authors.lastname: Symonds
mesh_terms: D000328:Adult; D017209:Apoptosis / Q000502:physiology*; D002467:Cell Nucleus / Q000737:chemistry / Q000648:ultrastructure; D004247:DNA / Q000032:analysis; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D015994:Incidence; D008854:Microscopy, Electron; D010920:Placenta / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure*; D011247:Pregnancy / Q000502:physiology*; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third
chemical_list: D004247:DNA