Siglec-1 expression and localization in the male reproductive tract of the dromedary camel during the rutting season.

Dromedary camels are of increasing economic importance; however, their reproductive efficiency remains suboptimal, and the immunological mechanisms underlying male reproductive function are still poorly understood. Sialic acid-binding immunoglobulin-like lectin 1 (Siglec-1) is an important immunomodulatory receptor in several mammalian tissues, but its expression and localization in the male reproductive tract (MRT) of camels have not previously been investigated. This study aimed to characterize the expression and localization of Siglec-1 in the MRT of adult dromedary camels during the rutting season. Tissue samples of testes, epididymis, and vas deferens were collected from 12 healthy adult camels (≥ 5 years old) and analyzed using quantitative real-time PCR, western blotting, and immunohistochemistry. Siglec-1 mRNA was detected in all examined tissues, with significantly higher expression in the caudal pole of the testis and vas deferens (p < 0.05). Western blot analysis confirmed the presence of Siglec-1 protein in all MRT segments. Immunohistochemistry revealed the localization of Siglec-1 in Leydig cells, Sertoli cells, spermatogenic cells, epididymal epithelial cells, and vas deferens epithelial cells. Semi-quantitative and quantitative analyses demonstrated significantly higher immunoreactivity in the caudal pole of the testis and vas deferens than in the remaining MRT regions (p < 0.05). In conclusion, Siglec-1 is widely distributed throughout the camel MRT, with prominent expression in the testis and vas deferens. To our knowledge, this is the first study to characterize Siglec-1 in the camel MRT. These findings suggest that Siglec-1 may contribute to reproductive immune regulation, epithelial barrier integrity, and sperm protection in dromedary camels.