Effects of cryopreservation on meiotic spindles of oocytes and its dynamics after thawing: clinical implications in oocyte freezing—a review article

Embryo freezing has been a successful practice, but oocyte cryopreservation formerly achieved poorer results. This was mainly due to low rates of survival, fertilization, and development. The major dissimilarities for oocytes to embryos are the character of the plasma membrane, the presence of corti...

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Bibliographic Details
Published in:Molecular and Cellular Endocrinology 2003-04, Vol.202 (1), p.101-107
Main Authors: Chen, S.U., Lien, Y.R., Chao, K.H., Ho, H.N., Yang, Y.S., Lee, T.Y.
Format: Article
Language:English
Subjects:
Animals
Cell Membrane - ultrastructure
Cell Size
Cell Survival
Chromosome Aberrations
Cryopreservation - methods
Cryoprotective Agents
Female
Fertilization in Vitro
Humans
In Vitro Techniques
Male
Meiosis
Meiotic spindle
Mice
Oocyte cryopreservation
Oocytes - ultrastructure
Pregnancy
Rabbits
Slow freezing
Sperm Injections, Intracytoplasmic
Temperature
Vitrification
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Summary:Embryo freezing has been a successful practice, but oocyte cryopreservation formerly achieved poorer results. This was mainly due to low rates of survival, fertilization, and development. The major dissimilarities for oocytes to embryos are the character of the plasma membrane, the presence of cortical granules, at the metaphase of meiosis II with the spindle system. In addition, the oocytes must be fertilized by sperm at the appropriate time. To improve the survival rate, a refined slow freezing method with increased sucrose concentration would dehydrate oocytes more sufficiently. Vitrification is another approach to prevent ice crystal formation. Intracytoplasmic sperm injection is used to overcome possible zona hardening from the release of cortical granules. The microtubules of meiotic spindles are vulnerable to the thermal changes and would depolymerize. Cryopreserved oocytes exhibited serious disturbances of the microtubules immediately after thawing. Fertilization of oocytes with disorganized spindles could lead to chromosomal aneuploidy, digyny, and arrest of cleavage. After incubation, the microtubules would repolymerize in a time-dependent way. Normal fertilization and development of cryopreserved oocytes improved after appropriate incubation and timing of insemination, compatible with recovery of the spindles. With the improvement of survival, fertilization, and cleavage, oocyte cryopreservation would gain an imperative role.
ISSN:0303-7207
1872-8057
DOI:10.1016/S0303-7207(03)00070-4