title: Qualitative and morphometric analysis of the ultrastructure of human oocytes cryopreserved by two alternative slow cooling protocols.
abstract: OBJECTIVE
  To ascertain possible cell damage from cryopreservation, the ultrastructure of human oocytes cryopreserved by slow cooling was assessed.
  
  
  METHODS
  Cryopreservation was performed through two protocols with one-step or two-step propanediol. Fresh control oocytes were examined for comparison. Samples were processed for transmission electron microscopy analysis.
  
  
  RESULTS
  By light microscopy, both fresh and frozen-thawed oocytes appeared regularly rounded, with intact zona pellucida, and homogeneous cytoplasm. By electron microscopy observation, organelles were abundant and uniformly dispersed. Mitochondria-smooth endoplasmic reticulum associations appeared regular. However, both the amount and density of cortical granules appeared abnormally reduced in frozen-thawed samples. Slight to moderate vacuolization was also found in the ooplasm of oocytes of both frozen groups.
  
  
  CONCLUSIONS
  Slow cooling ensures a good overall preservation of human oocytes. However, cytoplasmic vacuolization and cortical granule loss appears associated with cryopreservation, irrespective of the protocol used.
authors.affiliation: Tecnobios Procreazione, Centre for Reproductive Health, Bologna, Italy. coticchio@hotmail.it
authors.forename: Giovanni
authors.initials: G
authors.lastname: Coticchio
authors.forename: Andrea
authors.initials: A
authors.lastname: Borini
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Distratis
authors.forename: Marta
authors.initials: M
authors.lastname: Maione
authors.forename: Giulia
authors.initials: G
authors.lastname: Scaravelli
authors.forename: Veronica
authors.initials: V
authors.lastname: Bianchi
authors.forename: Guido
authors.initials: G
authors.lastname: Macchiarelli
authors.forename: Stefania A
authors.initials: SA
authors.lastname: Nottola
mesh_terms: D000328:Adult; D015925:Cryopreservation; D003451:Cryoprotective Agents / Q000494:pharmacology*; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D018871:Endoplasmic Reticulum, Smooth / Q000648:ultrastructure; D005260:Female; D005615:Freezing; D006801:Humans; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000648:ultrastructure; D009865:Oocytes; D009926:Organ Preservation; D011409:Propylene Glycols / Q000494:pharmacology*
chemical_list: D003451:Cryoprotective Agents; D011409:Propylene Glycols