{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,17]],"date-time":"2025-10-17T00:18:31Z","timestamp":1760660311335,"version":"build-2065373602"},"reference-count":46,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2025,10,16]],"date-time":"2025-10-16T00:00:00Z","timestamp":1760572800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001691","name":"Ministry of Education, Science, Sports, and Culture","doi-asserted-by":"publisher","award":["15K1588"],"award-info":[{"award-number":["15K1588"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"name":"journal Animals"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>Testicular stiffness is a potential indicator of spermatogenic activity. Herein, we investigated the relationship between testicular stiffness and intratesticular morphology in Syrian hamsters by using a robotic system with a micro-force sensor. Animals were divided into control, sham-operated, and surgically induced cryptorchidism groups. Testicular stiffness, testis weight and size, and Johnsen score data for sham and crypt groups were partially derived from our previous study and reanalysed. Testicular stiffness and histological parameters were analysed, including tunica albuginea thickness, seminiferous tubule occupancy, tubule diameter, intratubular cell-layer thickness, peritubular lamina propria thickness, and Leydig cell numbers. Compared with those of sham and normal controls, cryptorchid testes showed significantly lower stiffness and marked morphological changes, such as reduced tubule occupancy and diameter, thinner intratubular cell layers, thickened tunica albuginea and peritubular lamina propria, and increased numbers of Leydig cells. Decreased testicular stiffness and the Johnsen score, a standard index of spermatogenic function, were strongly related to these structural changes. These findings indicate that structural changes in the testes caused by impaired spermatogenesis are related to measurable differences in tissue stiffness. This study supports using mechanical properties as non-invasive quantitative indices to evaluate testicular function in animal models, offering a novel approach for future research in experimental andrology.<\/jats:p>","DOI":"10.3390\/ani15202999","type":"journal-article","created":{"date-parts":[[2025,10,16]],"date-time":"2025-10-16T12:17:02Z","timestamp":1760617022000},"page":"2999","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Morphological Analysis of Intratesticular Structures Affecting Hamster Testicular Stiffness"],"prefix":"10.3390","volume":"15","author":[{"given":"Shiki","family":"Hagino","sequence":"first","affiliation":[{"name":"Department of Animal Reproduction, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi 753-0841, Yamaguchi, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1683-8505","authenticated-orcid":false,"given":"Yoko","family":"Sato","sequence":"additional","affiliation":[{"name":"Department of Medical Engineering, Faculty of Allied Sciences, University of East Asia, Shimonoseki 751-8503, Yamaguchi, Japan"},{"name":"Department of Biology, School of Biological Sciences, Tokai University, Sapporo 005-8601, Hokkaido, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Miki","family":"Yoshiike","sequence":"additional","affiliation":[{"name":"Department of Urology, St. Marianna University of Medicine, Kawasaki 216-8511, Kanagawa, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shiari","family":"Nozawa","sequence":"additional","affiliation":[{"name":"Department of Urology, St. Marianna University of Medicine, Kawasaki 216-8511, Kanagawa, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-6054-3502","authenticated-orcid":false,"given":"Kenji","family":"Ogawa","sequence":"additional","affiliation":[{"name":"Faculty of Science and Technology, Keio University, Yokohama 223-8522, Kanagawa, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Daisuke","family":"Tomizuka","sequence":"additional","affiliation":[{"name":"Faculty of Science and Technology, Keio University, Yokohama 223-8522, Kanagawa, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Akane","family":"Kinebuchi","sequence":"additional","affiliation":[{"name":"Department of Biology, School of Biological Sciences, Tokai University, Sapporo 005-8601, Hokkaido, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yuna","family":"Tamakuma","sequence":"additional","affiliation":[{"name":"Department of Biology, School of Biological Sciences, Tokai University, Sapporo 005-8601, Hokkaido, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kohei","family":"Ohnishi","sequence":"additional","affiliation":[{"name":"Faculty of Science and Technology, Keio University, Yokohama 223-8522, Kanagawa, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0382-959X","authenticated-orcid":false,"given":"Takeshige","family":"Otoi","sequence":"additional","affiliation":[{"name":"Bio-Innovation Research Center, Tokushima University, Tokushima 779-3233, Tokushima, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3422-1904","authenticated-orcid":false,"given":"Masayasu","family":"Taniguchi","sequence":"additional","affiliation":[{"name":"Department of Animal Reproduction, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi 753-0841, Yamaguchi, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Teruaki","family":"Iwamoto","sequence":"additional","affiliation":[{"name":"Department of Urology, St. Marianna University of Medicine, Kawasaki 216-8511, Kanagawa, Japan"},{"name":"Division of Male Infertility, Sanno Hospital, Center for Human Reproduction for IVF, International University of Health and Welfare, Minato 107-0052, Tokyo, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,10,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"198","DOI":"10.1152\/physrev.1972.52.1.198","article-title":"Kinetics of spermatogenesis in mammals: Seminiferous epithelium cycle and spermatogonial renewal","volume":"52","author":"Clermont","year":"1972","journal-title":"Physiol. 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