@phdthesis{oai:obihiro.repo.nii.ac.jp:02000051,
 author = {井上, 裕士 and INOUE, Yuji},
 month = {2023-10-18, 2023-10-18, 2023-10-18},
 note = {2023, application/pdf, サラブレッド種は個々の経済的価値が高いため、生産性を向上させることは意義深い。生殖器疾患の診断および治療技術が年々進歩するに従い受胎率も向上してきたが、依然として原因不明の不妊症に遭遇する。
馬の卵巣や子宮に関しては比較的アプローチが容易であり、その部位が原因となる不妊症に対する診断や治療方法は改善されてきた。卵管の剖検所見ではコラーゲン塊が内在している症例が多く、その大きさによっては卵管の疎通性を障害し不妊の原因となり得ることが示唆されている。しかし、卵管性不妊に対する臨床的な診断、治療方法は確立されていない。これは馬の卵管子宮口は解剖学的に乳頭状に突出していて、発達した平滑筋により開口部が緊縮しているため、子宮腔から卵管内へのアプローチが困難であることに起因している。
一方、人の婦人科医療では子宮鏡観察下で卵管にカテーテルを留置し、卵管の疎通性を診断するための選択的卵管通水法が確立されている。
本研究の第2章では、大腸ファイバースコープによる観察下で子宮腔内から卵管子宮口に挿入可能なカテーテルを作成し、馬において内視鏡観察下で選択的卵管通水法が可能であるか検討した。その結果、作成したカテーテルは高い確率で卵管子宮口に挿入することが可能であり、そのカテーテルを通じて卵管内に色素を注入すると卵管やその周辺組織が着色したこと、また卵管采より漏出した色素により腹水が着色した症例があったことから、馬の卵管の疎通性を評価し得ることが判明した。
第3章では、第1章で確立した卵管通水法を用いて, 既存の診断方法では異常所見が認められない不妊馬において, 多くの剖検所見で認められる卵管内のゼラチン塊による卵管閉塞に起因して不妊症が発症していると仮定し, その細胞塊を卵管子宮口からの生理食塩水による通水で腹腔内に押しやることで卵管の再疎通を試みた。その処置後の受胎率を調べることで, その卵管通水法が妊孕性の改善に有効であるか検討した。その結果、内視鏡観察下で卵管子宮口にカテーテルを挿入し, 生理食塩水を通水する卵管通水法は, 卵管閉塞が疑われる不妊馬に対し受胎率を著しく向上させることができることが判明した。
本研究で開発された選択的卵管通水法は斬新であり、子宮腔内から卵管に非侵襲的に通水することが可能となったことから、今までほぼ不可能であった卵管性不妊を有する症例に対し、臨床的にその診断や治療に寄与できる方法を確立し得ることが示された。将来的には、卵管授精の確立や卵管機能の研究等を進展させる一助となり、馬の生産率向上に大きく貢献できることが示唆された。, Because of the high individual economic value of Thoroughbred horses, it is significant to improve their productivity. Although the fertility rate has been improved as the technology for diagnosing and treating reproductive diseases was progressed year by year, infertility of unknown causes is still encountered.
The ovaries and uterus of mares are relatively easy to approach, therefore, the diagnosis methods, especially ultrasonography, and treatment for infertility caused by the ovaries and uterus have been improved in recent years. On the other hand, clinical diagnosis and therapeutic methods for tubal infertility have not yet been established. This is because the uterotubal junction has a papilla-like structure and is constricted by well-developed smooth muscle in mares, making it anatomically difficult to approach the uterine tubes from the uterine cavity. However, autopsy findings show that collagenous masses are present in the uterine tubes in many cases. It has been suggested that depending on the size of the collagen masses, the patency of the uterine tubes may be impaired and that could be potential cause of infertility. In the past reports, most of researchers have attempted tubal cannulation through the fimbria by invasive methods using laparotomy or laparoscopy for suspected tubal infertility.
Compared to the anatomical structure of the uterine tube in horses, the human uterotubal junction does not have contracted smooth muscle and may open into the uterus, so that it is relatively easy to access into the uterine tube from uterine cavity. In human gynecological medicine, a selective hydrotubation has been established for diagnosing the patency of the uterine tubes by placing a catheter in the tubes under hysteroscopic observation.
In Chapter 2, which follows Chapter 1 (the introduction of this research), a catheter that can be inserted from the uterine cavity into the uterine tube under endoscopic observation through the working channel of a video endoscope was prepared using a polyethylene tube, an outer tube of an indwelling catheter and a guide wire for human angiography. Then 10 experimental mares were restrained in stocks and sedated, and a video endoscope was inserted into the uterus from the vulva. It was attempted to insert the catheters into the uterotubal junction at both uterine horns and dye was infused into the uterine tubes. After this procedure, abdominal fluid was obtained to identify color of the stain. In addition, a partial incision was made in the vaginal wall and another endoscope was inserted into the abdominal cavity to observe the ovaries, uterine tubes, and surrounding tissue directly. We investigated whether selective hysteroscopic hydrotubation is possible in mares by these procedures. As a result, the created catheter could be inserted into the uterotubal junction with a high probability and the dye solution was observed in the ampula and on surrounding tissue. In addition, peritoneal fluid was stained by the dye solution which could be leaked from the fimblia in some cases. From this result, it was clarified that hydrotubation is possible and this technique could be a potential diagnostic tool for oviductal patency in mares.
In Chapter 3, in 28 mares with unexplained infertility, assuming the cause is that a relatively large gelatin mass presented in the uterine tubes interferes with the passage of sperm and/or fertilized eggs, using the hysteroscopic hydrotubation established in Chapter 2, recovery of the oviductal patency was attempted by pushing the collagenous mass into the peritoneal cavity with flushing saline through the uterine tubes from uterotubal junction. Success with cannulation, pregnancy rate after treatment were researched and it was evaluated that whether this treatment is clinically useful for improving fertility. As a result, catheterization into the uterotubal junction was possible with a high probability regardless of the stage of the estrous cycle, and the conception rate after the procedure showed a high value regardless of the number of matings that did not lead to conception before the procedure. From this result, it was clarified that the hysteroscopic hydrotubation using saline could remarkably improve the conception rate in infertile mares suspected of having oviduct blockage.
The selective hysteroscopic hydrotubation developed in this research is novel and making it possible to perform non-invasive treatment. In addition, it is significant that the collagenous mass blocking the lumen of the uterine tube could be expelled into the peritoneal cavity from the extremely narrow isthmus through the ampulla which has a relatively large lumen. This study revealed that it will be possible to establish a method that can clinically contribute to the diagnosis and treatment for infertility caused by oviductal patency in mares. It was suggested that in the future, this technique is potential to help to establish oviduct insemination and advanced research for oviduct function. Also, it will contribute to improve production rate of horses., 博士学位論文, 大学院畜産学研究科},
 school = {帯広畜産大学},
 title = {馬の選択的卵管通水法に関する研究},
 year = {}
}