Morphology and topography of the external male genital organs of spotted paca (Cuniculus paca Linnaeus, 1766)

Abstract

Spotted paca (Cuniculus paca) is a rodent species from the family Cuniculidae, found in South America, from the Orinoco River Basin to Paraguay. Although widely studied with regard to its morphological and reproductive aspects, still there’re no records on the morphology of the male reproductive system in this species. Thus, this study aimed to evaluate not only the macro and microscopic anatomy of the external genital organs in this species, but also their topography. We studied the external genital organs of 10 adult spotted pacas; 5 specimens, fixed in a 10% aqueous formaldehyde solution, were macroscopically studied and from 5 specimens we collected fragments from the reproductive system, for microscopic analysis. The testicles showed a parenchyma structured in seminiferous tubules and the germinal epithelium rested on its basal membrane. These organs were located in the abdominal cavity, the inguinal path, or within the scrotum. Penis, fibroelastic, was located in the pubic region, in caudal direction. Its glans, coated by keratinized epithelium, were covered by the prepuce and, below this, we identified a slender cartilaginous structure with serrated edges. A couple of bone spurs was located into a bag ventral to the urethra, whose mucosa was lined by transitional epithelium. The epididymal duct was balled up in the head, had a body and tail, and its head was lined by pseudo-stratified stereociliated epithelium, and the tail by simple cubic epithelium; from this, the deferent duct stemmed, lined by columnar stratified epithelium.

Keywords

• Male reproductive organ
• Morphology
• Spotted paca