Fig. 5.
Presynaptic SADs regulate IaPSN-MN synaptic maturation. (A–F) In control Ia boutons (A and B), the vesicle marker VGLUT1 is closely apposed to the active zone marker Bassoon and the postsynaptic marker Shank1a. VLUT1 immunoreactivity extends into preterminal regions when SADs are deleted presynaptically from sensory neurons (arrows in C and D) but not postsynaptically from motor neurons (E and F). (G) Cumulative frequency histogram and bar graph showing enlargement of VGLUT1 bouton volume with presynaptic but not postsynaptic SAD deletion (graph shows mean ± SEM, n = 4 animals, n > 5,000 boutons, ***unpaired t test: P < 0.001 compared with control and SADChatCre). (Scale bars: 2 µm.)