Alterations of the cytoskeleton and polyploidy reduced by cryopreservation of metaphase II mouse oocytes

Ali Eroglu, T. L. Toth, Mehmet Toner

Research output: Contribution to journalArticle

135 Citations (Scopus)

Abstract

Objective: To determine cryopreservation-induced alterations in the cytoskeleton of metaphase II mouse oocytes and the implications of these alterations in functionality of the cytoskeleton and polyploidy after fertilization. Design: Comparative study. Setting: Clinical and academic research environment at a medical school teaching hospital. Intervention(s): Oocytes were frozen using a slow-cooling (0.5°C/min) and slow-thawing (8°C/min) protocol in 1.5 M dimethyl sulfoxide and 0.2 M sucrose and were analyzed before and after fertilization. Main Outcome Measure(s): Cytoskeletal alterations, fertilization, and polyploidy rates. Result(s): When analyzed immediately after thawing, the oocytes displayed dramatic cytoskeletal alterations. Only slight recovery was observed upon removal of the cryoprotectants. However, incubation after thawing of 1 hour at 37°C completely reestablished a normal microfilament and microtubule pattern while partially restoring normal spindle morphology and chromosome alignment. Accordingly, insemination immediately after removal of cryoprotectants resulted in a significantly decreased fertilization rate and aberrant dynamics of cytoskeleton-dependent events, whereas oocytes inseminated after the post-thaw incubation displayed fertilization rates and cytoskeletal dynamics comparable to those in controls. Cryopreservation did not increase polyspermy but significantly increased digyny when the oocytes were inseminated after the post-thaw incubation. All digynic eggs displayed an abnormal spindle remnant in comparison with diploid or polyspermic eggs. Conclusion(s): A brief period of incubation after thawing allows recovery and positively affects fertilization and cytoskeletal dynamics. Cryopreservation does not impair the functionality of microfilaments and cytoplasmic microtubules during postfertilization events. Our findings suggest that the increased rate of digyny in cryopreserved oocytes may be related to the spindle disorganization, leading to failure in segregation of the chromosomes, rather than to direct malfunction of the microfilaments in polar body formation.

Original languageEnglish (US)
Pages (from-to)944-957
Number of pages14
JournalFertility and Sterility
Volume69
Issue number5
DOIs
StatePublished - May 1 1998
Externally publishedYes

Fingerprint

Polyploidy
Cryopreservation
Metaphase
Cytoskeleton
Fertilization
Oocytes
Actin Cytoskeleton
Microtubules
Eggs
Polar Bodies
Chromosome Segregation
Insemination
Dimethyl Sulfoxide
Diploidy
Medical Schools
Teaching Hospitals
Sucrose
Chromosomes
Outcome Assessment (Health Care)
Research

Keywords

  • Cryopreservation
  • Cytoskeleton
  • Digyny
  • Fertilization
  • Oocyte

ASJC Scopus subject areas

  • Obstetrics and Gynecology

Cite this

Alterations of the cytoskeleton and polyploidy reduced by cryopreservation of metaphase II mouse oocytes. / Eroglu, Ali; Toth, T. L.; Toner, Mehmet.

In: Fertility and Sterility, Vol. 69, No. 5, 01.05.1998, p. 944-957.

Research output: Contribution to journalArticle

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