title: Focal spermatogenesis originates in euploid germ cells in classical Klinefelter patients.
abstract: BACKGROUND
  Klinefelter syndrome is the most frequent chromosome abnormality in human males. This paper aims to investigate the ploidy of meiotic and pre-meiotic germ cells found in spermatogenic foci, and furthermore, the sex chromosome constitution of Sertoli cells which surround these germ cells in non-mosaic Klinefelter patients.
  
  
  RESULTS
  A survey of 11 adult patients diagnosed with classical, non-mosaic Klinefelter syndrome who underwent testicular biopsies, showed that six of them had spermatogenesis foci. The topographical study of the biopsies showed that tubuli with germ cells are a minor fraction (8-24%) of all tubuli, although the overwhelming majority is devoid of germ cells. Using fluorescence in situ hybridization (FISH) with probes for the X-centromere and immunolocalization of meiotic proteins, the present work shows that all the 92 meiotic spermatocytes analyzed with FISH were euploid, 46,XY, and thus can form normal, haploid gametes. On the other hand, Sertoli cells show two marks for the X chromosome, meaning that they are 47,XXY.
  
  
  CONCLUSIONS
  These results provide a rationale for the high rate of success in the testicular sperm extraction plus ICSI procedures when applied to Klinefelter patients. It is also in agreement with previous studies in the XXY-mouse model. These spermatogenic foci most probably originate from clones of spermatogonia that have randomly lost one of the X chromosomes, probably during periods of life when high spermatogonial mitotic activity occurs.
authors.affiliation: Biología Celular, Facultad de Medicina, UBA, Paraguay 2155, C1121ABG Buenos Aires, Argentina.
authors.forename: R B
authors.initials: RB
authors.lastname: Sciurano
authors.forename: C V
authors.initials: CV
authors.lastname: Luna Hisano
authors.forename: M I
authors.initials: MI
authors.lastname: Rahn
authors.forename: S
authors.initials: S
authors.lastname: Brugo Olmedo
authors.forename: G
authors.initials: G
authors.lastname: Rey Valzacchi
authors.forename: R
authors.initials: R
authors.lastname: Coco
authors.forename: A J
authors.initials: AJ
authors.lastname: Solari
mesh_terms: D000328:Adult; D005854:Germ Cells / Q000502:physiology*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D007713:Klinefelter Syndrome / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D012708:Sertoli Cells / Q000473:pathology / Q000502:physiology; D013090:Spermatocytes / Q000473:pathology / Q000502:physiology; D013091:Spermatogenesis / Q000502:physiology*; D013737:Testis / Q000473:pathology*