Figure 2. The volume and number of geniculate ganglion neurons decrease in Bdnf^−/−/Ntf4^−/− and TrkB^−/− mice between E11.5 and E13.5.

(A) At E11.5, there was no difference between the geniculate ganglion volumes in wild-type, Bdnf^−/−/Ntf4^−/−, and TrkB^−/− mice. At E12.5, the geniculate ganglion volume was reduced by 36% and 76% in Bdnf^−/−/Ntf4^−/− and TrkB^−/− mice, respectively, compared with wild-type mice. The geniculate ganglion volume was significantly smaller in the TrkB^−/− compared with the Bdnf^−/−/Ntf4^−/− mice. There was a significant increase in the geniculate ganglion volume in wild-type mice at E13.5 compared with E11.5. There were significant reductions in the geniculate ganglion volumes of Bdnf^−/−/Ntf4^−/− and TrkB^−/− mice at E13.5, but no significant difference between the two mutant genotypes at this stage. (B) At E11.5, the number of geniculate neurons was reduced by 31% and 45% in the Bdnf^−/−/Ntf4^−/− and TrkB^−/− mice compared with the wild-type mice. At E12.5, the number of geniculate neurons was reduced by 48% and 81% in the Bdnf^−/−/Ntf4^−/− and TrkB^−/− mice, respectively, compared with the wild-type mice. There were also significantly fewer neurons in the TrkB^−/− mice than the Bdnf^−/−/Ntf4^−/− mice at E12.5. At E13.5, the number of geniculate neurons was reduced by 80% and 87% in Bdnf^−/−/Ntf4^−/− and TrkB^−/− mice, respectively, compared with the wild-type mice. There was no significant difference in the number of neurons between the two mutant genotypes at E13.5. *p<0.05, **p<0.01, and ***p<0.001.