Figure 7.

Presynaptic terminals in hippocampus CA1 of AS transgenic mice show extensive tubulovesicular architecture. Comparison of presynaptic nerve terminals found in the hippocampus CA1 (stratum radiatum) in non-Tg (top left, reconstruction in light blue with synapses in yellow) and AS-Tg mice (top right, reconstruction in green with synapses in red). Enlarged nerve terminals of AS-Tg mice show extensive membranous networks (middle row, white arrowheads) and form synapses (evidenced by postsynaptic densities and accumulation of presynaptic vesicles). Both EM analysis using SBEM (top two rows) and tomography (bottom row) revealed large presynaptic nerve terminals filled with tubulovesicular structures similar to what we observed in vitro. Segmentation of contiguous membrane segments from tomographic reconstruction is shown in three different colors (inset in bottom row, right, corresponding to the area indicated by arrowheads).