title: The effect of vitrification on ultrastructure of human in vitro matured germinal vesicle oocytes.
abstract: OBJECTIVE
  To describe the possible effects of cryotop vitrification on maturation rate and ultrastructural morphology of human in vitro matured germinal vesicle (GV) oocytes.
  
  
  METHODS
  A total of 301surplus immature GV oocytes obtained from infertile patients were allocated into two groups: (i) GV oocytes (n=150) matured in vitro (fIVM), and (ii) GV oocytes (n=151) that were first vitrified, then matured in vitro (vIVM). Supernumerary fresh in vivo matured oocytes (n=10) were used as controls. The maturation media was Ham's F10 supplemented with FSH+LH and human follicular fluid. After 36h of incubation, the oocytes were investigated for nuclear maturation and ultrastructural changes using transmission electron microscopy (TEM).
  
  
  RESULTS
  Oocyte maturation rates were reduced (P<0.001) in vIVM (45.92%) in comparison with fIVM oocytes (75.33%). The rate of degeneration was also significantly higher in vIVM than in the fIVM group (44.4% vs. 6.0%). Large and numerous mitochondria and minute vesicles of smooth endoplasmic reticulum (SER) complexes (MV complexes) were observed in both fIVM and vIVM groups. In addition, TEM revealed a drastic reduction in amount of cortical granules (CGs) at the cortex of vitrified-warmed GV oocytes, as well as appearance of vacuoles and small mitochondria-SER aggregates in the ooplasm.
  
  
  CONCLUSIONS
  The vitrification procedure is associated with ultrastructural alterations in specific oocyte microdomains, presumably related to the reduced competence of cryopreserved oocytes for maturation. This information emphasizes the need for further work on advancing the cryotechnology of human oocytes.
authors.affiliation: Department of Anatomy, Shahid Beheshti University of Medical Sciences, Tehran, Iran. abas_shahedi2006@yahoo.com
authors.forename: Abbas
authors.initials: A
authors.lastname: Shahedi
authors.forename: Ahmad
authors.initials: A
authors.lastname: Hosseini
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Khalili
authors.forename: Mohsen
authors.initials: M
authors.lastname: Norouzian
authors.forename: Mohammad
authors.initials: M
authors.lastname: Salehi
authors.forename: Abbas
authors.initials: A
authors.lastname: Piriaei
authors.forename: Stefania Annarita
authors.initials: SA
authors.lastname: Nottola
mesh_terms: D000328:Adult; D002470:Cell Survival; D016009:Chi-Square Distribution; D015925:Cryopreservation; D005260:Female; D006801:Humans; D059471:In Vitro Oocyte Maturation Techniques; D046529:Microscopy, Electron, Transmission; D009865:Oocytes / Q000254:growth & development* / Q000648:ultrastructure*; D058989:Vitrification; D055815:Young Adult