First Evidence of Siglec-10 Localization and Expression in Camel Male Reproductive Tissues and Spermatozoa: Potential Relevance to Fertility.

Siglec-10 is a cell-surface lectin that belongs to the sialic acid-binding immunoglobulin-like lectins (Siglecs) receptor involved in immune tolerance, but its role in reproduction remains unknown. Because immune regulation is essential for sperm survival and fertilization, Siglec-10 may represent an unexplored factor in camel fertility. Here, we investigated its expression and localization in the male reproductive tract and spermatozoa of dromedary camels during the rutting season. Testis, epididymis, and vas deferens were analyzed by immunohistochemistry and quantitative PCR, while spermatozoa from fresh ejaculates, frozen-thawed semen, and epididymal samples were examined using chromogenic and fluorescent immunostaining. Siglec-10 was strongly expressed in the testis and epididymis but absent in the vas deferens. In spermatozoa, the signal was localized mainly to the head and midpiece, with consistent patterns in fresh and frozen-thawed semen but absent in epididymal sperm. These findings provide the first descriptive evidence of Siglec-10 in camel reproductive tissues and ejaculated spermatozoa, suggesting a possible involvement in mechanisms that support sperm integrity under stress conditions; however, further studies are needed to clarify its functional role in semen preservation, and highlighting its relevance as a fertility biomarker in seasonal breeders.