title: Spontaneous in vitro maturation of oocytes prior to ovarian tissue cryopreservation in natural cycles of oncologic patients.
abstract: OBJECTIVE
  To evaluate the recovery rate and spontaneous in vitro maturation (IVM) of immature oocytes enclosed within or released from follicles during the processing of ovarian tissue prior to its cryopreservation.
  
  
  METHODS
  Thirty-three oncologic patients who had not previously undergone chemo or radiotherapy underwent ovarian tissue cryopreservation (OTC) during natural menstrual cycles. Immature oocytes, enclosed within follicles or released during ovarian cortex processing, were collected and matured spontaneously in vitro for 48 h. Nuclear maturation was assessed every 24 h and the ability of the IVM oocytes to display a normal activation response following parthenogenetic activation was evaluated. The following outcome measures were also evaluated: disease, age, FSH, LH, E2, P4 and AMH serum levels, menstrual cycle day, recovery and spontaneous IVM and parthenogenetic activation rates.
  
  
  RESULTS
  Oocytes recovered per patient were 3.3 ± 0.7 (1.8-4.7 oocytes, 95CI), regardless of the menstrual phase. The mean number of IVM oocytes per patient was 1.3 ± 0.2 oocytes (95CI: 0.8-1.8), regardless of menstrual phase (p = 0.86) and oocyte origin (p = 0.61). Forty-one percent of oocytes extruded the second polar body and formed one pronucleus after parthenogenetic activation.
  
  
  CONCLUSIONS
  Twenty-one of the 33 women (63.6 %) requesting OTC produced at least one mature oocyte.
authors.affiliation: Universitary Institute IVI Valencia, Valencia, Spain. mariajose.escriba@ivi.es
authors.forename: María-José
authors.initials: MJ
authors.lastname: Escribá
authors.forename: Noelia
authors.initials: N
authors.lastname: Grau
authors.forename: Laura
authors.initials: L
authors.lastname: Escrich
authors.forename: Edurne
authors.initials: E
authors.lastname: Novella-Maestre
authors.forename: María
authors.initials: M
authors.lastname: Sánchez-Serrano
mesh_terms: D000328:Adult; D015925:Cryopreservation / Q000379:methods*; D005260:Female; D059247:Fertility Preservation / Q000379:methods*; D006801:Humans; D009369:Neoplasms / Q000150:complications*; D009865:Oocytes / Q000502:physiology* / Q000648:ultrastructure; D009926:Organ Preservation / Q000379:methods*; D006080:Ovarian Follicle; D010053:Ovary / Q000166:cytology / Q000502:physiology*; D010312:Parthenogenesis