Cholinergic neurons in the nucleus tegmenti pedunculopontinus pars compacta and the caudoputamen of the rat: a light and electron microscopic immunohistochemical study using a monoclonal antibody to choline acetyltransferase.

Large neurons in the nucleus tegmenti pedunculopontinus pars compacta (TPC) of the rat were shown to have choline acetyltransferase (ChAT) immunoreactivity by light and electron microscopic immunohistochemistry using a monoclonal antibody to ChAT. The ChAT-positive TPC neurons had triangular or multipolar cell bodies with diameters of 20-50 micron. The ultrastructural features of the ChAT-positive TPC neurons were similar to those of ChAT-positive neurons in the caudoputamen; each neuron had a distinct, pale nucleus with an indented nuclear envelope and large, cytoplasm-containing, well-developed endoplasmic reticulum and pale mitochondria.