Microanatomy of the Testes and Male Genital Ducts of Banded Krait Bungarus fasciatus (Schneider, 1801)

The Banded krait is a species of venomous snakes that ranks among the top 5 in Thailand, with a significance role as a predator for controlling other animals. Despite numerous studies on the ecology, the microanatomy of body systems has still not reported clearly. The present study was to investigate the microanatomy of the testes and male genital ducts of Banded krait that collected from Phatthalung Province, Thailand. The snakes were collected after anesthetized, and their testes and genital ducts were fixed in Bouin’s fixative. The reproductive organs were collected during July to October 2022, and were sectioned of 5-µm-thick pieces for staining with Harris’s hematoxylin and eosin (H&E), periodic acid Schiff’s (PAS), alcian blue (AB) pH 2.5 and pH 1.0, bromophenol blue (BB) and Masson’s trichrome (MT). The testes contained the seminiferous tubules with 7 stages of germ cells: (I) type A spermatogonium, (II) type B spermatogonium, (III) primary spermatocyte, (IV) secondary spermatocyte, (V) round spermatid, (VI) elongated spermatid and (VII) spermatozoa. Besides, Sertoli and Leydig’s cells were appeared in the seminiferous tubules and the interstitial area, respectively. During the sampling period, the spermatozoa were observed in the seminiferous tubules and genital ducts. The extra-testicular rete testis, ductuli efferentes and ductus epididymis were embedded in the epididymal sheath. The epithelial cells of rete testis, ductus epididymis, as well as ductus deferens possessed microvilli, whereas those of the ductuli efferentes composed of cilia. The epithelial cells of all portions showed the positive staining with PAS and BB due to the presence of neutral glycoproteins and proteins, respectively, and the negative staining for AB pH 2.5 and pH 1.0 because of the absence of acidic glycoproteins. HIGHLIGHTS During the sampling period from July to October, the Banded Krait exhibited active spermatogenesis The rete testis could be divided into 2 portions: intra-rete testis and extra-rete testis The ductus epididymis was divided into 3 portions: proximal, middle and distal ductus epididymis All portions of the male genital ducts, the epithelium showed the secretion of neutral glycoproteins and proteins without sulfated and carboxylated glycoproteins GRAPHICAL ABSTRACT