title: Proliferation of germ cells and somatic cells in first trimester human embryonic gonads as indicated by S and S+G2+M phase fractions.
abstract: OBJECTIVE
  The number of germ cells and somatic cells in human embryonic and foetal gonads has previously been estimated by stereological methods, which are time- and labour-consuming with little information concerning cell proliferation. Here, we studied whether flow cytometry could be applied as an easier method, also enabling estimation of the fraction of cells in S or S+G(2)+M (SG(2) M) cell-cycle phases as indicators of cell proliferation.
  
  
  METHODS
  Cell suspensions from 35 human embryonic gonads at days 37 to 68 post-conception (pc) were immunomagnetically sorted into C-KIT positive (germ) cells and negative (somatic) cells. They were stained for DNA content and analysed by flow cytometry. S and SG(2) M fractions could be measured for 13 of the female and 20 of the male gonads. The number of cells was estimated using fluorescent reference beads.
  
  
  RESULTS
  During the period from 37 to 68 days pc, female germ and somatic cells had a stable S and SG(2) M fractions indicating steady growth of both subpopulations, whereas they decreased in both male germ and somatic cells. The number of germ and somatic cells estimated by flow cytometry was significantly lower than in stereological estimates, suggesting loss of cells during preparation.
  
  
  CONCLUSIONS
  Cell proliferation as indicated by S and SG(2) M fractions could be estimated specifically for primordial germ and somatic cells. Estimation of total number of germ and somatic cells was not feasible.
authors.affiliation: Laboratory of Reproductive Biology, Section 5712, University Hospital of Copenhagen, Rigshospitalet, Copenhagen, Denmark.
authors.forename: K P
authors.initials: KP
authors.lastname: Sørensen
authors.forename: M C
authors.initials: MC
authors.lastname: Lutterodt
authors.forename: L S
authors.initials: LS
authors.lastname: Mamsen
authors.forename: A G
authors.initials: AG
authors.lastname: Byskov
authors.forename: J K
authors.initials: JK
authors.lastname: Larsen
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D049109:Cell Proliferation; D002469:Cell Separation; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D005456:Fluorescent Dyes / Q000494:pharmacology; D005854:Germ Cells / Q000166:cytology*; D006066:Gonads / Q000166:cytology / Q000196:embryology; D006801:Humans; D018189:Immunomagnetic Separation; D008297:Male; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D019009:Proto-Oncogene Proteins c-kit / Q000096:biosynthesis; D020298:U937 Cells
chemical_list: D005456:Fluorescent Dyes; D019009:Proto-Oncogene Proteins c-kit; D000469:Alkaline Phosphatase