The effects of sialoadenectomy and exogenous EGF on taste bud morphology and maintenance

Taste buds on the dorsal tongue surface are continually bathedin saliva rich in epidermal growth factor (EGF). In the followingexperiment, taste bud number and morphology were monitored followingsubmandibular and sublingual salivary gland removal (sialoadenectomy),to determine if EGF plays a role in the maintenance and formationof taste buds. Adult male rats were divided into four groups:sialoadenectomized (SX, n = 4); sialoadenectomized with EGFreplacement (SX + EGF, n = 5); sham-operated (SH, n = 4); andsham-operated with exogenous EGF (SH + EGF, n = 5). After a3 week recovery, SX + EGF and SH + EGF animals were given 50µg/day EGF in their drinking water for 14 days. At day14, saliva was collected, the animals were killed and the presenceof EGF determined by radioligand-binding assay. Tongues wereremoved and histologically examined for the presence and morphologyof taste buds on fungiform and circumvallate papillae, or immunostainedfor the presence of EGF, TGF