@article {Kaneko:2005:1532-0820:140, author = "Kaneko, Takehito and Nakagata, Naomi", title = "Relation between Storage Temperature and Fertilizing Ability of Freeze-Dried Mouse Spermatozoa", journal = "Comparative Medicine", volume = "55", number = "2", year = "2005", abstract = "The advantage of freeze-dried mouse spermatozoa is that samples can be stored in the refrigerator (+4°C). Moreover, the storage of freeze-dried spermatozoa at ambient temperature would permit spermatozoa to be shipped easily and at low cost around the world. To examine the influence of the storage temperature on freeze-dried spermatozoa, we assessed the fertilizing ability of spermatozoa stored at different temperatures. Cauda epididymal spermatozoa were freeze-dried in buffer consisting of 50 mM ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid, 50 mM NaCl, and 10 mM Tris-HCl (pH 8.0). Samples of freeze-dried spermatozoa were stored at −70, −20, +4, or +24°C for periods of 1 week and 1, 3, and 5 months. Sperm chromosomes were maintained well at −70, −20, and +4°C for 5 months, and oocytes fertilized with these spermatozoa developed to normal offspring. Moreover, the chromosomal integrity of spermatozoa stored at −20 or +4°C did not decrease even after 17 months. In contrast, the chromosomes of spermatozoa stored at +24°C were maintained well for 1 month but became considerably degraded after 3 months. In addition, to investigate the cause of deterioration of sperm chromosomes during storage at +24°C, spermatozoa were freeze-dried in buffer containing DNase I. The chromosomes of spermatozoa freeze-dried with 1 or 0.2 units/ml of DNase I, 100% or 72%, respectively, exhibited chromosomal abnormalities. Our findings suggest that freeze-dried spermatozoa can be stored long-term with stability at +4°C, and the suppression of nucleases present in the buffer or spermatozoa during storage led to the achievement of long-term storage of freeze-dried spermatozoa.", pages = "140-144", url = "http://www.ingentaconnect.com/content/aalas/cm/2005/00000055/00000002/art00005" }