title: Full-term development of rats from oocytes fertilized in vitro using cryopreserved ejaculated sperm.
abstract: For preservation of rat spermatozoa, the general-purpose method requires that the male be sacrificed for collection of spermatozoa from the epididymides. However, it would be highly useful if the ejaculated spermatozoa could be successfully cryopreserved and the frozen-thawed spermatozoa used for in vitro fertilization, since this would allow the genetically valuable rats to be maintained alive rather than sacrificed. The aim of the present study was to clarify whether ejaculated rat spermatozoa could be successfully cryopreserved and fertilized in vitro. The motility and viability of frozen-thawed ejaculated spermatozoa were similar to those of frozen-thawed epididymal spermatozoa (around 10%). The percentage of acrosomal integrity in epididymal spermatozoa was significantly higher than that in ejaculated spermatozoa after freezing/thawing. The level of capacitation-associated protein tyrosine phosphorylation in frozen-thawed ejaculated sperm was slightly increased at 5h. When the frozen-thawed ejaculated spermatozoa were used for in vitro fertilization, the percentages of fertilization, pronuclear formation, and development to the 2-cell stage (26.5%, 23.0%, and 91.0%, respectively) were similar to those of frozen-thawed epididymal spermatozoa (19.4%, 15.0%, and 84.1%, respectively). However, the rate of blastocyst formation in the ejaculated group was significantly lower than that in the epididymal group (12.0% vs 43.2%). Results from the embryo transfer experiment showed that the proportions of embryos developed to term were similar between the ejaculated (47.7%) and epididymal groups (53.7%). We showed here for the first time that ejaculated spermatozoa can be cryopreserved and the frozen-thawed sperm could be developed to term via in vitro fertilization in rats.
authors.affiliation: Laboratory of Animal Reproduction, Graduate School of Veterinary Science, Azabu University, Sagamihara, Japan.
authors.forename: Yasunari
authors.initials: Y
authors.lastname: Seita
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Fujiwara
authors.forename: Akiko
authors.initials: A
authors.lastname: Takizawa
authors.forename: Koji
authors.initials: K
authors.lastname: Furukawa
authors.forename: Tomo
authors.initials: T
authors.lastname: Inomata
authors.forename: Junya
authors.initials: J
authors.lastname: Ito
authors.forename: Naomi
authors.initials: N
authors.lastname: Kashiwazaki
mesh_terms: D000818:Animals; D004542:Ejaculation; D005307:Fertilization in Vitro / Q000379:methods*; D008297:Male; D009865:Oocytes / Q000502:physiology*; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D012662:Semen Preservation / Q000379:methods*