Figure 11.

Three dimensional reconstruction of multisynaptic hippocampal termination in the nucleus reuniens. Three dimensional reconstruction from serial EM (case BQ, Alexa488 tracer). A hippocampal axon termination (blue) forms five distinct synapses with the shaft and thorns of a CR excitatory thalamic relay dendrite (CR+ ED, light green). The axon termination also forms four synapses with shafts of inhibitory dendrites (ID, orange or pink). One of these inhibitory dendrites also forms a synapse with the CR+ excitatory thalamic relay dendrite. A, Asymmetric (excitatory, shades of green) synapses formed by hippocampal axon termination with thorns or shaft of CR+ ED or with IDs. Also shown is a symmetric (inhibitory) synapse (darker red) between one of the IDs and the CR+ ED. Scale box, 1 µm³ B, Same scenes with the addition of the hippocampal axon termination (blue). C, Same scenes with the addition of the CR+ ED (light green). D, Same scenes with the addition of two IDs (light pink and orange). E, Same scenes with the addition of the remaining two IDs (darker pinks). Grey scale box, 1 µm³. CBL, Cascade Blue; CR, calretinin; ED, excitatory relay dendrite; Hipp, hippocampus; ID, inhibitory dendrite.