Meiotic spindle dynamics in human oocytes following slow-cooling cryopreservation

John Bromfield, Giovanni Coticchio, K. Hutt, Raffaella Sciajno, Andrea Borini, David F. Albertini

Research output: Contribution to journalArticleResearchpeer-review

83 Citations (Scopus)

Abstract

BACKGROUND: The demand for cryopreservation of human oocytes is increasing in assisted reproduction clinics and yet remains an experimental procedure. Surprisingly, little is known about the effects of cryopreservation on spindle-chromosome interactions and the recovery of meiotic spindle functionality. The goal of these studies was to evaluate the process of meiotic spindle reassembly and chromosome alignment in cryopreserved human metaphase II oocytes. METHODS: Unfrozen control oocytes were compared with frozen oocytes fixed at 0, 1, 2 and 3 h after thawing. Oocytes were analysed by confocal microscopy and subjected to 3-dimensional image analysis to evaluate spindle integrity. RESULTS: Freezing resulted in a loss of spindle bipolarity and chromosome alignment. One hour following thawing, most oocytes recovered spindle bipolarity and equatorial chromosomal alignment. However, between 2 and 3 h, a progressive loss of chromosome alignment was observed. Further analysis revealed a positive correlation between spindle length and number of displaced chromosomes following freezing. This time-dependent redistribution of chromosomes involved outward displacement from the equatorial plate and retention at the surface of the meiotic spindle. CONCLUSIONS: Spindle disassembly incurred by cryopreservation is rapidly reversed and is coordinated with chromosome alignment within 1 h but is not sustained at later times.

Original languageEnglish
Pages (from-to)2114-2123
Number of pages10
JournalHuman Reproduction
Volume24
Issue number9
DOIs
Publication statusPublished - Sept 2009
Externally publishedYes

Keywords

  • Chromosome alignment
  • Cryopreservation
  • Meiotic spindle
  • Microtubule
  • Oocyte

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