{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T17:08:51Z","timestamp":1790615331099,"version":"4.1.0"},"reference-count":36,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T00:00:00Z","timestamp":1790553600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>In lizards, the longitudinal canal conveys the sperm from the rete testis to the ductuli efferentes, which connect to the cranial end of the epididymal duct. Due to its reduced extension, the longitudinal canal has been largely ignored compared with the ductuli efferentes and the ductus epididymis. The objective of this study was to provide information on the structure and function of the longitudinal canal in the lizard Podarcis siculus by using light and transmission electron microscopy. For this purpose, testes and epididymides from adult male P. siculus lizards captured during the reproductive period were used. Light microscopy showed that the longitudinal canal was lined by a simple squamous or low cuboidal epithelium containing apical periodic acid-Schiff (PAS)-positive granules. Transmission electron microscopy revealed two types of epithelial cells: ciliated and non-ciliated. The non-ciliated cells showed electron-dense granules in the supranuclear and apical regions, suggesting probable secretory activity. These findings demonstrate, for the first time, that the longitudinal canal of the lizard Podarcis siculus is not merely a passageway for the sperm but may play a role in the composition of the medium in which these gametes are found during their flow towards the epididymis.<\/jats:p>","DOI":"10.3390\/ani16193057","type":"journal-article","created":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T15:57:57Z","timestamp":1790611077000},"page":"3057","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Secretory Activity in the Longitudinal Canal of Male Podarcis siculus Lizards"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8580-7556","authenticated-orcid":false,"given":"Salvatore","family":"Desantis","sequence":"first","affiliation":[{"name":"Department of Precision and Regenerative Medicine and Ionian Area (DiMePre-J), University of Bari Aldo Moro, 70124 Bari, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-7985-1743","authenticated-orcid":false,"given":"Antonio Ciro","family":"Guaricci","sequence":"additional","affiliation":[{"name":"Department of Precision and Regenerative Medicine and Ionian Area (DiMePre-J), University of Bari Aldo Moro, 70124 Bari, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0495-8975","authenticated-orcid":false,"given":"Mario","family":"Cinone","sequence":"additional","affiliation":[{"name":"Department of Precision and Regenerative Medicine and Ionian Area (DiMePre-J), University of Bari Aldo Moro, 70124 Bari, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8937-3860","authenticated-orcid":false,"given":"Maria","family":"Albrizio","sequence":"additional","affiliation":[{"name":"Department of Precision and Regenerative Medicine and Ionian Area (DiMePre-J), University of Bari Aldo Moro, 70124 Bari, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1155","DOI":"10.1016\/j.ympev.2007.05.015","article-title":"The phylogeny of the family Lacertidae (Reptilia) based on nuclear DNA sequences: Convergent adaptations to arid habitats within the subfamily Eremiainae","volume":"44","author":"Mayer","year":"2007","journal-title":"Mol. Phylogenet. Evol."},{"key":"ref_2","first-page":"407","article-title":"Podarcis siculus (Rafinesque\u2013Schmaltz, 1810)","volume":"Volume 4","author":"Corti","year":"2011","journal-title":"Fauna d\u2019 Italia: Reptilia"},{"key":"ref_3","unstructured":"Rondinini, C., Battistoni, A., Peronace, V., and Teofili, C. (2013). Lista Rossa IUCN dei Vertebrati Italiani."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"836","DOI":"10.1643\/0045-8511(2002)002[0836:FTASAI]2.0.CO;2","article-title":"Freeze Tolerance and Supercooling Ability in the Italian Wall Lizard, Podarcis sicula, Introduced to Long Island, New York","volume":"2002","author":"Burke","year":"2002","journal-title":"Copeia"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"364","DOI":"10.31610\/trudyzin\/2020.324.3.364","article-title":"Podarcis siculus (Reptilia: Sauria: Lacertidae), a new alien species for Russian fauna","volume":"324","author":"Tuniyev","year":"2020","journal-title":"Proc. Zool. Inst. RAS"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Rosati, L., Chianese, T., Simoniello, P., Motta, C.M., and Scudiero, R. (2022). The Italian wall lizard Podarcis siculus as a biological model for research in male reproductive toxicology. Int. J. Mol. Sci., 23.","DOI":"10.3390\/ijms232315220"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1080\/11250007609434890","article-title":"Influence of photoperiod and temperature on the testicular activity of the lizard, Lacerta s. sicula Raf","volume":"43","author":"Angelini","year":"1976","journal-title":"Boll. Zool."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1080\/11250008409439459","article-title":"Reproductive models and strategies in vertebrate evolution","volume":"51","author":"Angelini","year":"1984","journal-title":"Boll. Zool."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"113579","DOI":"10.1016\/j.ygcen.2020.113579","article-title":"Spermatogenesis and regulatory factors in the wall lizard Podarcis sicula","volume":"298","author":"Rosati","year":"2020","journal-title":"Gen. Comp. Endocrinol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"181","DOI":"10.1111\/j.1463-6395.2006.00231.x","article-title":"Histological variation along and ultrastructural organization of the epithelium of the ductus epididymides of the fan-throated lizard Sitana ponticeriana Cuvier","volume":"87","author":"Akbarsha","year":"2006","journal-title":"Acta Zool."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1111\/j.1463-6395.2007.00278.x","article-title":"Efferent ductules of the fan-throated lizard Sitana ponticeriana Cuvier: Light and transmission electron microscopy study","volume":"88","author":"Akbarsha","year":"2008","journal-title":"Acta Zool."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"2176","DOI":"10.1002\/ar.21282","article-title":"Proximal testicular ducts of the mediterranean gecko (Hemidactylus turcicus)","volume":"293","author":"Rheubert","year":"2010","journal-title":"Anat. Rec."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"104","DOI":"10.1002\/jmor.10784","article-title":"Ultrastructure of the reproductive system of the black swamp snake (Seminatrix pygaea). VI. Anterior testicular ducts and their nomenclature","volume":"271","author":"Sever","year":"2010","journal-title":"J. Morphol."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Vetere, A., Capasso, M., and Di Ianni, F. (2025). Sex Determination in Reptiles: A Review. Animals, 15.","DOI":"10.3390\/ani15020168"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Robaire, B., and Hinton, B.T. (2002). Evolution of the vertebrate epididymis. The Epididymis: From Molecules to Clinical Practice, Kluwer Academic.","DOI":"10.1007\/978-1-4615-0679-9"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1111\/azo.12270","article-title":"Microanatomy of the testes and testicular ducts of the butterfly lizard, Leiolepis ocellata Peters, 1971 (Reptilia: Squamata: Agamidae) during the active reproductive period","volume":"101","author":"Pewhom","year":"2020","journal-title":"Acta Zool."},{"key":"ref_17","first-page":"420","article-title":"Die samenableitungswege der eidechsen","volume":"6","author":"Alverdes","year":"1926","journal-title":"Z. Mikrosk. Anat. Forsch."},{"key":"ref_18","first-page":"205","article-title":"Ricerche sperimentali sui pori femorali e sull\u2019epididimo della Lucertola (Lacerta muralis Laur.) considerati come caratteri sessuali secondari","volume":"31","author":"Padoa","year":"1933","journal-title":"Arch. Ital. Anat. Embriol."},{"key":"ref_19","unstructured":"Gans, C., and Parsons, T.S. (1977). The urogenital system of reptiles. Biology of the Reptilia, Morphology, Academic Press. Volume 6, Morphology."},{"key":"ref_20","first-page":"405","article-title":"Die epididymis der Sauropsiden im Vergleich zu S\u00e4ugetier und Mensch","volume":"15","author":"Alverdes","year":"1928","journal-title":"Z. Mikrosk. Anat. Forsch."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"331","DOI":"10.1002\/jmor.1050720208","article-title":"The normal seasonal reproductive cycle in the male Eumeces fasciatus together with some observations on the effects of castration and hormone administration","volume":"72","author":"Reynolds","year":"1943","journal-title":"J. Morphol."},{"key":"ref_22","first-page":"290","article-title":"Seasonal variation of the male urogenital organs of Scincus scincus L. and Chalcides ocellatus Forsk","volume":"160","author":"Badir","year":"1958","journal-title":"Zeit Wissenschaft. Zool."},{"key":"ref_23","first-page":"47","article-title":"Glycoconjugates during the annual sexual cycle in lizard epididymal ductuli efferentes: A histochemical study","volume":"41","author":"Labate","year":"1997","journal-title":"Eur. J. Histochem."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1023\/A:1020986313281","article-title":"Evidence of regional differences in the lectin histochemistry along the ductus epididymis of the lizard, Podarcis sicula Raf","volume":"34","author":"Desantis","year":"2002","journal-title":"Histochem. J."},{"key":"ref_25","unstructured":"Mazzi, V. (1977). Metodo Alcian-PAS. Manuale di Tecniche Istologiche e Istochimiche, Piccin Ed."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Capaldo, A. (2023). The adrenal gland of Squamata (Reptilia): A comparative overview. Animals, 13.","DOI":"10.3390\/ani13172686"},{"key":"ref_27","first-page":"1","article-title":"Gonaden und susf\u00fchrungsg\u00e4nge","volume":"Volume 6","author":"Bolk","year":"1933","journal-title":"Vergleichenden Anatomie der Wirbelthiere"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Rheubert, J.L., Siegel, D.S., and Trauth, S.E. (2014). Male reproductive anatomy: The gonads, gonadoducts, sexual segment of the kidney, and cloaca. Reproductive Biology and Phylogeny of Lizards and Tuatara, CRC Press.","DOI":"10.1201\/b17961"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1206\/310.1","article-title":"Phylogeny and systematics of Squamata (Reptilia) based on morphology","volume":"310","author":"Conrad","year":"2008","journal-title":"Bull. Am. Mus. Nat. Hist."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Pyron, R.A., Burbrink, F.T., and Wiens, J.J. (2013). A phylogeny and revised classification of Squamata, including 4161 species of lizards and snakes. BMC Evol. Biol., 13.","DOI":"10.1186\/1471-2148-13-93"},{"key":"ref_31","first-page":"201","article-title":"Histochemical analysis of lizard testicular glycoconjugates during the annual spermatogenetic cycle","volume":"39","author":"Labate","year":"1995","journal-title":"Eur. J. Histochem."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"635","DOI":"10.1002\/mrd.22500","article-title":"Sugar-coated sperm: Unraveling the functions of the mammalian sperm glycocalyx","volume":"82","author":"Tecle","year":"2015","journal-title":"Mol. Reprod. Dev."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1002\/ar.1092170207","article-title":"Endocytic apparatus and transcytosis in the epithelial cells of the vas deferent in the rat","volume":"217","author":"Hermo","year":"1987","journal-title":"Anat. Rec."},{"key":"ref_34","unstructured":"Skinner, M.K. (2018). Rete testis: Structure, cell biology and site for stem cell transplantation. Encyclopedia of Reproduction, Academic Press Elsevier. [2nd ed.]. Chapter: 47."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1530\/jrf.0.0740023","article-title":"Acquisition of sperm motility and its maintenance during storage in the lizard, Lacerta vivipara","volume":"74","author":"Depeiges","year":"1985","journal-title":"J. Reprod. Fertil."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"432","DOI":"10.1002\/jemt.1070290604","article-title":"Structure and function of the ductuli efferentes: A review","volume":"29","author":"Ilio","year":"1994","journal-title":"Microsc. Res. Tech."}],"container-title":["Animals"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2615\/16\/19\/3057\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T16:17:30Z","timestamp":1790612250000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2615\/16\/19\/3057"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,28]]},"references-count":36,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2026,10]]}},"alternative-id":["ani16193057"],"URL":"https:\/\/doi.org\/10.3390\/ani16193057","relation":{},"ISSN":["2076-2615"],"issn-type":[{"value":"2076-2615","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,28]]}}}