Figure 8. 3D models based on electron microscopy tomograms of WT and Dyn1 KO synapses following high K+ stimulation.
The models illustrate the abundance and morphology of HRP-labeled bulk endosomes (yellow) in nerve terminals from WT (A and B, a 600 nm thick volume) and Dyn1 KO (C and D, an 800 nm volume) neuronal cultures stimulated for 90 s with high K+ in the presence of soluble HRP and recovered for 1 min in HRP-free buffer. PM is shown in green. B and D show the same nerve terminals of A and B after subtraction of bulk endosomes to reveal SVs (blue) and CCPs (green). CCPs are shown in the same green as the plasma membrane as they are all connected to this membrane by long narrow tubules (see a direct connection to the plasma membrane in the inset of D). No CCPs are present on bulk endosomes. The postsynaptic density is shown in red. Scale bars: A–D, 100 nm. (E and F) Gallery of individual bulk endosomes in WT and Dyn1 KO nerve terminals, respectively.