Spermatozoa in the sexual segment of the kidney and urogenital morphology of male Monocled Cobras, Naja kaouthia Lesson, 1831, from Ang Thong Province, Thailand

Abstract

The Monocled Cobra (Naja kaouthia) is a medically important elapid, widely distributed across South and Southeast Asia. However, the functional roles of the urogenital system, particularly the secretions of the sexual segment of the kidney (SSK) and their interactions with spermatozoa in male squamates remain poorly understood. We examined the macro- and microscopic anatomy of the male urogenital system in seven adult N. kaouthia specimens obtained post-mortem from local farmers in Ang Thong Province, central Thailand. Histological analyses revealed testes in recrudescence, spermiogenesis, and spermiation stages, with spermatozoa present in the ductus epididymis and ductus deferens during active testicular stages. The kidneys exhibited marked variation in SSK development, varying from hypotrophied to maximally hypertrophied tubules. Notably, spermatozoa were observed within the lumen of the SSK, collecting ducts, and ureters. These findings provide anatomical evidence that contributes to the understanding of the functional role of the SSK in elapid snakes and other squamates.