Morphology of the nasal cavities and associated structures in <i>Artibeus jamaicensis</i> and <i>Myotis lucifugus</i>

Abstract

Abstract Anatomical differences in olfactory structures point to a more highly developed olfactory sense in the frugivorous bat Artibeus jamaicensis than in the insectivorous bat Myotis lucifugus. Artibeus' nostrils show greater potential for differential control of nasal airstreams. Its nasal cavities, in contrast to Myotis , are clearly demarcated into olfactory and respiratory portions. Both species have seven turbinals, but of the five ethmoturbinals, Artibeus has four endoturbinals and one ectoturbinal whereas Myotis has three and two, respectively. The configuration and histology of the more complex turbinals of Artibeus indicates a greater surface area of olfactory epithelium. The nasal epithelia are thicker in Artibeus . Olfactory receptors appear similar in both species but the thickness and composition of the olfactory epithelium in Artibeus suggests the presence of about twice as many receptors per unit area. This is also reflected in the relative prominence of olfactory nerve bundles. From these and other bulbar relationships we conclude that the proportion of fila olfactoria to large mitral cells, as reflected by the olfactory bulb glomeruli, is some function of a fundamental 2:1 relationship. Nasal glands, with flaps covering two of their more prominent ducts, and blood vessels are more pronounced in Artibeus . This presumably correlates with the nasal type of phonation exhibited by this bat as well as a greater ability to condition air per se. Nasopalatine ducts exist in both species but only Artibeus has a vomeronasal organ. A diffuse ganglion accompanies the organ; some of its neurons are associated with the unmyelinated vomeronasal nerve, whereas others are intraepithelial. The vomeronasal nerve terminates in a prominent accessory olfactory bulb.