　ナイロン糸に鉄製金属管を装着し，ストロー外部から磁石で操作できるガラス化用具を考案した。このガラス化用具を用いると，胚の超急速ガラス化後，ストロー内保存，さらには，加温時にストロー内でのガラス化液希釈が可能である。この手法で保存した体外受精胚を緩慢冷却法の凍結胚を対照として，加温または融解して，それぞれの生存率および透明帯脱出率を比較検討した。その結果，本手法による超急速ガラス化胚の生存率は緩慢冷却法と比べて有意に高く（培養72時間：94％vs 66％），同様に，透明帯脱出率も有意に高かった（培養72時間：89％vs 51％）。これらのことから，本手法は超急速ガラス化したウシ体外受精胚のストロー内での加温およびガラス化液希釈を可能にし，生存率および透明帯脱出率が向上することが明らかとなった。　

　Survivability of Vitrified Bovine Embryos Produced in Vitro Using Nylon Thread (2) Developmental method of vitrification solution diluted in a straw. KASA Shojiro, Miyuki MORI and Syuji UEDA (Fukuoka Agricultural Research Center, Chikushino, Fukuoka 818-8549, Japan) Bull. Fukuoka. Agric. Res. Cent. 25:99-103 (2006)

　A vitrification straw apparatus which is composed of a nylon thread attached to an iron metal tube was created. This apparatus can be operated with a magnet from the exterior of the straw. With the use of the apparatus, bovine embryo was preserved in the straw after rapid vitrification. Moreover, while the straw is being warmed, the vitrification solution can be diluted within the same straw. The survival rate of bovine embryo obtained and preserved in vitro with this technique was compared with embryo preserved by a slow cooling method as a control and warmed or thawed for a comparative examination for each survival rate and hatched zona pellucida. Consequently, it was found that the rate of survival of a rapid vitrification embryo using this technique was significantly higher compared with embryos preserved by the slow cooling method (94% vs. 66%), and the rate of hatched zona pellucida was also significantly higher (89% vs. 51%). This technique enabled warming and vitrification solution dilution within the straw in which bovine embryo has been preserved in vitro by means of rapid vitrification. These findings made it clear that the rate of survival and hatched zona pellucida improved.