title: Maturation outcomes are improved following Cryoleaf vitrification of immature human oocytes when compared to choline-based slow-freezing.
abstract: OBJECTIVE
  The cryopreservation of immature oocytes permits oocyte banking for patients at risk of losing their fertility. However, the optimum protocol for such fertility preservation remains uncertain.
  
  
  METHODS
  The present study investigated the survival, maturation, cytoskeletal and chromosome organization of sibling immature oocytes leftover from controlled ovarian stimulation cycles, that were either slow-frozen (with choline-substitution) or vitrified. A comparison group included oocytes that were never cryopreserved.
  
  
  RESULTS
  Among the three groups, comparable rates were observed for both survival (67-70%) and polar body extrusion (59-79%). Significantly more oocytes underwent spontaneous activation after IVM following slow-freezing compared with either vitrification or no cryopreservation. Likewise, the incidence of spindle abnormalities was greatest in the slow-frozen group, with no differences in spindle morphometrics or chromosome organization.
  
  
  CONCLUSIONS
  While the overall incidence of mature oocytes with normal bipolar spindles from warmed immature oocytes was low, the yield using Cryoleaf vitrification was slightly superior to choline-based slow-freezing.
authors.affiliation: Biology Department, Middlebury College, Middlebury, VT 05753, USA. ccombell@middlebury.edu
authors.forename: Catherine M H
authors.initials: CM
authors.lastname: Combelles
authors.forename: S Temel
authors.initials: ST
authors.lastname: Ceyhan
authors.forename: Haiyan
authors.initials: H
authors.lastname: Wang
authors.forename: Catherine
authors.initials: C
authors.lastname: Racowsky
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology; D002794:Choline; D002877:Chromosomes, Human / Q000502:physiology; D015925:Cryopreservation / Q000379:methods*; D006801:Humans; D008870:Microtubules / Q000502:physiology; D009865:Oocytes / Q000166:cytology* / Q000502:physiology; D058989:Vitrification
chemical_list: D002794:Choline
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