Meeting Abstract
The enigmatic Harderian gland (HG), an orbital gland, is connected to the vomeronasal organ (VNO: an accessory olfactory organ) via the nasolacrimal duct (NLD) in many tetrapod vertebrates. Though not all three are always present, at least one is found in any given tetrapod clade. When fully connected (snakes and frogs), the secretions of the HG pass though the NLD and into the VNO, presumably to act as a solvent for odorants. In primates and other mammals, the NLD no longer connects to the VNO. Instead, it is reduced to a vertical canal ending in the inferior meatus (e.g., monkeys), or it drains orbital fluids toward the external nose (e.g., lemurs and lorises). Whether the VNO still requires access these fluids (e.g., through the nasopalatine duct) is unclear. Yet, an alternative exists since the VNO has co-opted nearby nasal septal glands into vomeronasal glands. Very little is known about the structure, function or composition of such gland secretions. Tear specific lipocalin (TSL), an antimicrobial binding protein, has been identified in the orbital fluid of various tetrapods. By using immunohistochemical techniques, we found TSL present in the vomeronasal glands of three New World monkeys (marmoset, tamarin and black-headed spider monkey). In strepsirrhine primates, however, the TSL reactivity ranged from light staining (fat-tailed dwarf lemur, ring-tailed lemur, bushbaby and potto) to absent (loris). The precise role of TSL in the vomeronasal system remains to be determined. However, it is striking that TSL reactivity was stronger and more consistent in New World monkeys, all of which lack any route for HG secretions to reach the VNO.
