title: Chromosome size, morphology, and gene density determine bivalent positioning in metaphase I human spermatocytes.
abstract: OBJECTIVE
  To determine whether there is a preferential bivalent distribution pattern in metaphase I human spermatocytes and to analyze whether this positioning is influenced by chiasmata count, chromosome size, gene density, acrocentric morphology, and heterochromatic blocks.
  
  
  METHODS
  Proximity frequencies of bivalents were evaluated with the analysis of meiotic preparations combining sequentially standard techniques and multiplex fluorescence in situ hybridization.
  
  
  METHODS
  University.
  
  
  METHODS
  Twenty-five men consulting for fertility problems.
  
  
  METHODS
  Unilateral testicular biopsies.
  
  
  METHODS
  Proximity analyses were performed for each bivalent considering as nearby bivalents those that were part of the first ring around the bivalent studied. Data were analyzed using Poisson regression models, multidimensional scaling, and cluster analysis.
  
  
  RESULTS
  Some bivalents have a preferential relative position. Significant associations among bivalents related to chromosome size, high gene density, and acrocentric morphology were observed. Chiasmata count and heterochromatic blocks were nonconditioning parameters of the bivalent organization.
  
  
  CONCLUSIONS
  This study demonstrates that distribution in metaphase I is nonrandom and influenced by chromosome size, gene density, and acrocentric chromosome morphology. Results support that some features defining chromosome territories are maintained during meiosis.
authors.affiliation: Unitat de Biologia Cel·lular, Facultat de Biociències, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain.
authors.forename: Laia
authors.initials: L
authors.lastname: Vergés
authors.affiliation: Unitat de Biologia Cel·lular, Facultat de Biociències, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Blanco
authors.affiliation: Servei d'Estadística Aplicada, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain.
authors.forename: Oliver
authors.initials: O
authors.lastname: Valero
authors.affiliation: Unitat de Biologia Cel·lular, Facultat de Biociències, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain.
authors.forename: Francesca
authors.initials: F
authors.lastname: Vidal
authors.affiliation: Unitat de Biologia Cel·lular, Facultat de Biociències, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain. Electronic address: zaida.sarrate@uab.cat.
authors.forename: Zaida
authors.initials: Z
authors.lastname: Sarrate
mesh_terms: D048429:Cell Size; D022004:Chromosome Structures / Q000502:physiology; D002875:Chromosomes / Q000235:genetics*; D006801:Humans; D007248:Infertility, Male / Q000175:diagnosis* / Q000235:genetics*; D008297:Male; D008677:Metaphase / Q000235:genetics*; D013090:Spermatocytes / Q000473:pathology* / Q000502:physiology*
keywords: Bivalent; chromosome territories; meiosis; metaphase I; spermatocytes