Electron micrograph showing BDA-labeled terminals and WGA-HRP-labeled soma and dendrites in the brainstem of a rat.

<p>WGA-HRP was injected into the XII of the rat and BDA into its ipsilateral Vc. BDA-labeled S-type terminals (T) containing spherical vesicles make asymmetric synapses with dendrites (D) of HRP-labeled premotor neurons (a). Two BDA-labeled terminals (T1, T2) make asymmetric synapses simultaneously with dendrite of HRP-labeled premotor neuron (b). A BDA-labeled terminal makes asymmetric synapses simultaneously with one HRP-labeled spine (S2), one negative dendrite (D) and one negative spine (S1) (c). One negative terminal makes asymmetric synapse with HRP-labeled dendrite (d). The arrowheads indicate postsynaptic specializations. a and b are taken from the dorsal medullary reticular formation, c and d from the parvicellular reticular formation. Scale bars = 0.5 µm in a; 0.35 µm in b and c and 0.45 µm in d.