New ways to go—nasal floor structures as channelling system for vomeronasal stimuli in the shrew (Sorex araneus, Mammalia)

Abstract

The mammalian lateral nasal gland (LNG, also called Steno’s gland) is known to be one source of so-called odorant-binding proteins, which are suggested to work as vehicles to carry chemosensory stimuli within the nasal cavity in order to guide them to olfactory and vomeronasal sensory neurons. Up to now, a largely unattended and unanswered question is how the secretions of the LNG migrate between the glandular opening at the upper edge of the anterior lateral nasal wall and the more caudally located vomeronasal organ. In order to address this issue, the functional morphology of the rostral nasal cavity of Sorex araneus was investigated histologically. Special interest was laid on the opening region of the LNG in the vestibular region of the nose and its topological connection to a hitherto largely unnoticed nasal concha, the atrioturbinate. It appears that the atrioturbinate serves as a specialised channel that directs the secretions of the LNG pointedly towards the entrance of the vomeronasal organ. In addition, it was observed that—contrary to previous reports—the LNG in Sorex araneus is anatomically clearly separated from the maxillary sinus gland and does not invade the maxillary sinus.