Figure 11. Electron micrographs of single synapses in the ventrolateral medulla of Atp1a2^+/+ or Atp1a2^+/− and Atp1a2^−/− mice.

A, representative examples of presynaptic terminals with normal gross structural Atp1a2^+/+ and Atp1a2^−/− features. Note the presence of fewer synaptic vesicles in the presynaptic region in Atp1a2^−/− mice. B, quantitative analysis of synaptic vesicles (SV). Number of vesicles per μm² of presynaptic region of embryonic day 18.0–18.5 Atp1a2^+/+ or Atp1a2^+/− (n= 4) and Atp1a2^−/− (n= 4) fetuses. Atp1a2^−/−+ stim (n= 3) received repeated stimulation with 100 nm substance P. Data are means ±s.e.m.*P < 0.04.