title: Fertilization, embryo development, and clinical outcome of immature oocytes from stimulated intracytoplasmic sperm injection cycles.
abstract: OBJECTIVE
  To evaluate the fertilization and developmental potential of immature oocytes obtained from controlled ovarian hyperstimulated cycles of patients undergoing intracytoplasmic sperm injection (ICSI).
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  Academic assisted reproductive technology program.
  
  
  METHODS
  Two hundred patients with at least one mature oocyte and one immature oocyte (study 1), and 44 patients with no mature oocytes (study 2) at time of oocyte denudation.
  
  
  METHODS
  Oocyte denudation was performed immediately after retrieval. Oocytes were cultured in vitro for 4-6 hours before ICSI and then categorized into four groups: group I, metaphase II (MII) oocytes at denudation; group II, in vitro matured MII oocytes; group III, metaphase I (MI) oocytes that did not progress to MII; and group 4, germinal-vesicle (GV) oocytes that converted to MI.
  
  
  METHODS
  Fertilization and embryo development were compared among groups in study 1. Pregnancy and implantation rates were evaluated in study 2.
  
  
  RESULTS
  Although the fertilization rate in group III was significantly lower than in groups I and II, no significant difference was found between groups I and II. Day 3 embryos in group I had the highest mean number of blastomeres, proportions of good embryos, and blastocyst formation rate when compared with groups II and III. Two clinical pregnancies were achieved from 26 transfer cycles in study 2, resulting in pregnancy and implantation rates of 7.7% and 4% per transfer cycle, respectively.
  
  
  CONCLUSIONS
  Although our results show that immature oocytes from stimulated cycles can be normally fertilized and used to increase the number of embryos available for transfer, the increase in number of embryos derived from immature oocytes cannot be efficiently translated into pregnancies and live births. The clinical significance of using immature oocytes in stimulated cycles needs further investigation.
authors.affiliation: In Vitro Fertilization Program, Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Stanford University Medical Center, Stanford, California, USA.
authors.forename: Yimin
authors.initials: Y
authors.lastname: Shu
authors.forename: Janice
authors.initials: J
authors.lastname: Gebhardt
authors.forename: Jill
authors.initials: J
authors.lastname: Watt
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lyon
authors.forename: Danny
authors.initials: D
authors.lastname: Dasig
authors.forename: Barry
authors.initials: B
authors.lastname: Behr
mesh_terms: D000328:Adult; D004624:Embryo Transfer; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D005306:Fertilization / Q000502:physiology; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D008297:Male; D009865:Oocytes / Q000254:growth & development*; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology; D012189:Retrospective Studies; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods*