title: Cryopreservation of human prophase I oocytes collected from unstimulated follicles.
abstract: OBJECTIVE
  To evaluate the cryopreservation of immature human oocytes obtained from unstimulated ovarian tissue.
  
  
  METHODS
  Immature prophase I oocytes were obtained from unstimulated follicles and were either cryopreserved or cultured as controls. Cryopreservation was performed in a programmable freezing machine using one of two protocols. Method I (n = 133) used a one-step addition of cryoprotectant followed by a slow freeze and thaw protocol. With method II (n = 95), the cryoprotectant was added in a stepwise manner with cryopreservation performed in the presence of 0.2 M sucrose followed by rapid freezing and thawing.
  
  
  METHODS
  Basic research center at a medical school.
  
  
  METHODS
  Patients undergoing oophorectomy for nonovarian pathology.
  
  
  METHODS
  Rates of survival and maturation to metaphase II were compared between control oocytes and oocytes cryopreserved with methods I and II.
  
  
  RESULTS
  With method I, a survival rate of 15.6% was obtained with 58.3% of surviving oocytes reaching metaphase II after culture compared with 50.0% of nonfrozen control oocytes. Method II produced a survival rate of 43.3% with 27.3% maturing to metaphase II. Maturation of control oocytes for method II was 46.4%. Although the survival rate with method II was significantly higher than with method I, the rate of in vitro maturation to metaphase II showed no difference.
  
  
  CONCLUSIONS
  These results demonstrate that human prophase I oocytes obtained from unstimulated antral follicles are capable of meiotic maturation after cryopreservation.
authors.affiliation: Department of Obstetrics and Gynecology, The Jones Institute for Reproductive Medicine, Eastern Virgina Medical School, Norfolk 23507.
authors.forename: T L
authors.initials: TL
authors.lastname: Toth
authors.forename: S E
authors.initials: SE
authors.lastname: Lanzendorf
authors.forename: B A
authors.initials: BA
authors.lastname: Sandow
authors.forename: L L
authors.initials: LL
authors.lastname: Veeck
authors.forename: W A
authors.initials: WA
authors.lastname: Hassen
authors.forename: K
authors.initials: K
authors.lastname: Hansen
authors.forename: G D
authors.initials: GD
authors.lastname: Hodgen
mesh_terms: D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D015925:Cryopreservation / Q000379:methods*; D005260:Female; D006801:Humans; D008677:Metaphase; D008854:Microscopy, Electron; D009865:Oocytes / Q000166:cytology* / Q000502:physiology / Q000648:ultrastructure; D006080:Ovarian Follicle / Q000166:cytology*; D011418:Prophase