Mice (Mus musculus) lacking a vomeronasal organ can discriminate MHC-determined odortypes.

Major histocompatibility complex (MHC) genes in mammals (H-2 in mice) play a major role in regulating immune function. They also bestow individuality in the form of a chemical signature or odortype. At present, the respective contributions of the olfactory epithelium and the vomeronasal organ (VNO) in the recognition of individual odortypes are not well defined. We examined a possible role for the VNO in the recognition of MHC odortypes in mice by first removing the organ (VNX) and then training the mice to distinguish the odors of two congenic strains of mice that differed only in their MHC type. C57BL/6J mice (bb at H-2) and C57BL/6J-H-2(k) (kk at H-2) provided urine for sensory testing. Eight VNX and six sham-operated mice were trained to make the discrimination. Neither the number of training trials-to-criterion nor the rate of learning differed significantly for VNX and sham-operated mice. We conclude that the VNO is not necessary for learning to discriminate between MHC odortypes.

Evidence that taste buds are not present on the human adult uvula.

We conducted a study to investigate whether taste buds are present on the human adult uvula. Our impetus was to determine whether surgical procedures that involve removal of the uvula can affect taste perception. Five human uvulae were removed via a modified carbon dioxide laser-assisted uvulopalatoplasty in an outpatient office setting. The uvulae were serially sectioned and stained with a solution specific for membrane-bound calcium-modulated adenosine triphosphatase, a high concentration of which is found in taste receptors. Examination of the stained sections under light microscopy failed to show that any taste receptors were present in any of the uvulae. This finding suggests that the taste disturbances noted after surgical procedures involving removal of the uvula are not attributable to a loss of taste receptors.