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Updated: Jul 9, 2026
Mouse Sperm Cryopreservation and Recovery using the I·Cryo Kit
Published on: December 12, 2011
Mouse and human spermatozoa can be freeze-dried without damaging their chromosomes
H Kusakabe1, R Yanagimachi, Y Kamiguchi
1Department of Biological Sciences, Asahikawa Medical College, 2-1-1-1 Midorigaoka-higashi, Asahikawa 078-8510, Japan. hkusa55@asahikawa-med.ac.jp
Background:
Although mouse spermatozoa can be freeze-dried without losing their reproductive capacity, the technique needs further improvements to reduce the incidence of chromosomal damage to spermatozoa. Effects of freeze-drying on human spermatozoa are unknown.
Methods:
Mouse spermatozoa were suspended in a Tris-buffered EGTA solution briefly (10 min at 37 degrees C) or for 1-7 days at 4 degrees C before freeze-drying. Freeze-dried spermatozoa were maintained for up to 1 year at 4 degrees C before injection. Sperm chromosomes were examined during the first mitosis (cleavage) of zygotes. The ability of sperm to support embryo development was assessed by examining mid-gestation fetuses (Day 14) after transfer of 2-cell embryos to surrogate mothers. Chromosome integrity of freeze-dried human spermatozoa was examined by injecting individual spermatozoa into mouse oocytes which were previously enucleated.
Results:
When mouse spermatozoa were freeze-dried immediately after suspension in Tris-buffered EGTA solution, only c.40% had normal chromosomes. When the mouse spermatozoa were kept in the same solution for 3-7 days before freeze-drying, 85-95% had normal chromosomes and they were able to support embryo development better than those which were in the solution briefly (P < 0.05). Freeze-dried human spermatozoa well maintained their chromosomes regardless of the duration of pre-freeze-drying incubation of spermatozoa in the Tris-buffered EGTA solution.
Conclusions:
Prior incubation of mouse spermatozoa in Tris-buffered EGTA solution for several days makes sperm chromosomes more resistant to freeze-drying. As the consequence, spermatozoa freeze-dried this way support embryo development better than those exposed to Tris-buffered EGTA solution only briefly. Freeze-dried human spermatozoa well maintained their chromosomes without pre-freeze-drying incubation in Tris-buffered EGTA solution.
Insights
Pre-incubation of mouse sperm in a specific solution for several days significantly improves chromosome integrity after freeze-drying, enhancing embryo development. Human sperm showed stable chromosomes post-freeze-drying without this pre-incubation.
Area of Science:
- Reproductive biology
- Cryobiology
- Spermatozoa preservation
Background:
- Mouse spermatozoa can be freeze-dried, but chromosomal damage is a concern.
- The impact of freeze-drying on human spermatozoa remains unknown.
Purpose of the Study:
- To improve freeze-drying techniques for spermatozoa.
- To assess the effects of freeze-drying on human sperm chromosome integrity.
Main Methods:
- Mouse spermatozoa were incubated in Tris-buffered EGTA solution for varying durations before freeze-drying.
- Sperm chromosome integrity was analyzed post-thaw.
- Embryo development was assessed after injecting freeze-dried sperm into zygotes.
- Human sperm chromosome integrity was evaluated using an in vitro assay.
Main Results:
- Pre-incubation of mouse spermatozoa for 3-7 days increased normal chromosome rates to 85-95% post-freeze-drying.
- Sperm freeze-dried after longer incubation supported better embryo development.
- Freeze-dried human spermatozoa maintained chromosome integrity irrespective of pre-incubation duration.
Conclusions:
- Extended incubation in Tris-buffered EGTA enhances mouse sperm resistance to freeze-drying damage.
- This improved technique leads to better embryo development outcomes.
- Human spermatozoa exhibit inherent stability during freeze-drying without pre-incubation.
