Postnatal development of von Ebner's glands: accumulation of a protein of the lipocalin superfamily in taste papillae of rat tongue.

Antibodies produced against rat von Ebner's gland (VEG) protein, a recently characterized member of a lipophilic ligand carrier protein family, detect this protein immunocytochemically in von Ebner's gland acini and show that it is present at high concentrations in the clefts of circumvallate and foliate papillae. During embryonic development, von Ebner's gland anlagen are innervated (as shown immunocytochemically using neuronal specific antibodies) as early as embryonic day 20, before lateral glandular outgrowth and VEG protein can be observed. Expression of the VEG protein as determined by in situ hybridization and immunocytochemistry begins at postnatal day-2 cells in differentiating and branching off from von Ebner's gland ducts, and sharply increases with further enlargement and maturation of the gland. The close temporal correlation of von Ebner's gland innervation and VEG protein expression with papilla innervation and taste-bud development suggests a functional relationship of both structures. VEG protein might control access of lipophilic sapid molecules, such as bitter substances, to the gustatory receptors.