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. 2014 Jan 18;33(3):247–264. doi: 10.1002/embj.201387110

Figure 1.

Figure 1

Developmental changes in morphology of hair cell afferent synapses.
  1. Projection of confocal images showing GluA2/3 (green), RIBEYE (magenta) across the basal region of a row of IHCs at p6 (left) and p20 (right). Scale bar, 2 μm.
  2. Single confocal sections. Upper left: At p6, the basal pole of each IHC was contacted by several patches of postsynaptic glutamate receptors (GluA2/3, blue) forming circular structures (highlighted by dashed lines in upper right and lower left). Upper right: Each GluA2/3 spot was juxtaposed to an AZ spot, marked by protein bassoon (green) and in some cases by a ribbon (RIBEYE, red). Two ribbonless AZs marked by colocalizing bassoon and GluA2/3 puncta were highlighted by arrowheads. Individual fluorescence channels are presented separately in gray scale below. Scale bars, 2 μm.
  3. Schematized distribution of ribbon, bassoon, Ca2+ channels and GluA2/3-containing receptors on immature (p6, upper) and mature (p20, lower) IHC-SGN contacts. Immature IHC-SGN contacts hold multiple AZ/PSD complexes. Mature IHC-SGN contacts show a single and larger AZ/PSD complex.
  4. Projection of confocal images showing GluA2/3 (blue), RIBEYE (red), and Na+/K+-ATPase α3 subunit (green) at p6 (left) and p20 (right). The latter antibody labels the membranes of SGNs, each of which terminates onto the IHC with a bouton-type contact. In p6 preparations, the large circular structures formed by GluA spots partially encompass the perimeter of the bouton contacts. At p20, each postsynaptic bouton contains only a single condensed glutamate receptor cluster that is juxtaposed to a single presynaptic ribbon. Scale bars, 2 μm.