Development of the vomeronasal organ in Rousettus leschenaulti (Megachiroptera, Pteropodidae).

A functional vomeronasal organ (VNO) is known to be lacking in adult bats of the suborder Megachiroptera, family Pteropodidae, studied to date. However, whether the VNO every forms during ontogeny in megachiropterans has not been addressed. We report here on the development of the VNO in megachiropterans via study of 8 stages of rousette fruit bat Rousettus leschenaulti, ranging from an early limb bud embryo to a young specimen attached to the nipple. A vomeronasal primordium appears in the 4 youngest stages (7-14 mm crown-rump length), but there is no sign of any of the components of the vomeronasal system (neuroepithelial tube, nerves, sinuses, glands, or trough-like cartilage) in the septal region of the 4 oldest stages examined, or in the adult. Given the number of genera investigated to date and their taxonomic diversity, a conclusion that a VNO is entirely lacking in Megachiroptera seems reasonable. However, final confirmation awaits study of the additional 27 genera not yet reported (out of a total of 41).