In the absence of BDNF, taste buds are significantly smaller in size. Mean taste bud volumes for taste buds located in the tongue were plotted for wild-type, Bdnf−/−, Ntf4/5−/−, and Bdnf−/−/Ntf4/5−/− mice. Deletion of BDNF resulted in a drastic reduction in taste bud volume as compared to wild-type volumes. However, in the absence of NT-4, the surviving taste buds retained their normal size. Bdnf−/−/Ntf4/5−/− mice had very small taste buds, which were even smaller than those in BDNF mutant mice, indicating that in the absence of BDNF, the presence or absence of NT-4 does influence taste bud size. *P < 0.05 versus wild-type.