Figure 7
From: PLCγ-activated signalling is essential for TrkB mediated sensory neuron structural plasticity
Histological evidence for the inability of calyx formation in TrkbPLC/PLC point mutants. (A) Adapted scheme showing major differences between type I and type II hair cells. (B-C) Light microscopy pictures showing the appearance of utricular sensory epithelia at postnatal day 100 with large calyceal spaces around type I hair cells in the TrkbWT/WT control (asterisks) (B), compared to little calyx formation in the TrkbPLC/PLC mutant mice (asterik) (C); arrows in both panel B and C indicate the stereocilia suggesting that hair cells are normally developed. Braces "{" indicate the supporting cells (SP), or the hair cells (HC). (D-E) Electron microscopy (EM) micrographs showing a typical type I hair cell in the utricle of TrkbPLC/PLC mutant mice mostly without a fully formed calyx in vivo. However, in the striola region there is an occasional type I hair cell with a fully formed calyx (E) in the utricle of TrkbPLC/PLC mutant mice. (F) A canal cristae type I hair cell of the TrkbPLC/PLC mutants innervated by several afferent only forming partial calices and efferent boutons (H). The existence of two types of hair cells is verified by the examination of hair cell apices, which show the presence of two different sizes of stereocilia and mitochondria but no calyx (G) as previously described [19, 47]. Scale bars, 100 μm (panels B-C), 10 μm (panels D-F), (G-H are twice the magnification of F).