低温保存した犬精巣上体から回収した精巣上体尾部精子の凍結保存とそれを用いた人工授精(臨床繁殖学) Unilateral Intrauterine Insemination with Cryopreserved Caudal Epididymal Sperm Recovered from Refrigerated Canine Epididymides(Theriogenology)

犬精巣上体を摘出直後に4℃で48時間保存した後, 回収した精巣上体尾部精子の性状および凍結保存した後の性状を評価した.さらに, 凍結保存した精子の受精能を確認するために, 子宮内人工授精を行った.その結果, 4℃で48時間保存した精巣上体尾部から回収した精子の回収直後の精子活力(61.0%)は, 0および24時間保存に比較して有意に低値を示した(88.6%および80.7%).しかし, 回収後凍結保存した場合においては, 融解後の精子活力には差がみられなかった(0, 24および48時間保存群: 27.9, 24.3, 28.3%).回収直後の精子奇形率は, 保存を行わなかった0時間保存群(5.6%)に比較して, 24および48時間保存群において有意に高値を示し(19.3%および27.7%), 凍結融解後も精子奇形率は有意に高かった.細胞質小滴を付着した未熟精子の出現率は, 回収直後は0時間保存群(4.7%)に比較して, 48時間保存群で有意に高値を示した(18.4%)が, 凍結融解後にはその差がみられなかった.片側子宮内授精(精子数2×10^8)の結果, 5頭中4頭(80%)が受胎した.以上のことから, 摘出後4℃で48時間保存した精巣上体から回収し, 凍結保存した犬精巣上体尾部精子は融解後, 精子奇形率は高値を示したが, 精子活力は良好であり, 子宮内人工授精により高い受胎率が得られることが証明された.

Canine epididymides were excised and immediately stored at 4℃ for 48hr, and the qualities of caudal epididymal sperm after recovery and cryopreservation were evaluated. To confirm the fertility of the cryopreserved caudal epididymal sperm, artificial intrauterine insemination was performed. The sperm motility (61.0%) immediately after recovery from caudal epididymis stored at 4℃ for 48hr was significantly lower than those of sperm stored for 0 and 24hr (88.6 and 80.7%, respectively), but there was no significant difference after freeze-thawing (0-, 24-, and 48-hr storage groups : 27.9, 24.3, and 28.3%, respectively). The incidence of abnormal sperm immediately after recovery was significantly higher in the 24-hr and 48-hr storage groups (19.3 and 27.7%, respectively) than in the 0-hr storage group (5.6%), and a significant difference was also observed after freeze-thawing. The incidence of immature sperm with cytoplasmic droplets was significantly higher in the 48-hr storage group (18.4%) than in the 0-hr storage group (4.7%), but there was no difference after freeze-thawing. By unilateral intrauterine insemination (2×10^8 sperm), 4 of 5 bitches (80%) conceived. The above findings demonstrated that sperm motility was good even enough the incidence of abnormal sperm was high in canine epididymal sperm that were recovered from the epididymis stored at 4℃ for 48hr and cryopreseved, and that artificial intrauterine insemination resulted in a high conception rate.