Figure 8.

Connectivity of the VAChT-containing boutons in the external plexiform layer. (A–D) Series of ultrathin sections showing the connectivity of a VAChT-containing bouton in the external plexiform layer. A dendritic spine (s) receives two symmetrical synaptic contacts (arrowheads): One from a VAChT-containing bouton (electrondense DAB precipitate) and other from a non-cholinergic axon (ax). Note that, although the VAChT-containing bouton is beside the large dendrite of a principal cell (M/T), there are no synaptic contacts from the cholinergic axon on the principal cell (open arrows). Arrows point to dendro-dendritic reciprocal synaptic contacts between the principal cell and the gemmule of a granule cell (g). Scale bar: 500 nm.