Localization of acetylcholinesterase in autonomic nerves of the rat anococcygeus muscle.

Using the histochemical method by Karnovsky and Roots, localization of acetylcholinesterase (AChE) activity has been examined in the autonomic nerves of the rat anococcygeus muscle. The SPG fluorescence method for adrenergic nerves was also employed. By light microscopy the anococcygeus muscle received a much scarcer innervation of lightly stained fibres displaying the AChE reaction than it did of adrenergic fibres. At the ultrastructural level, occasional axons of both adrenergic and non-adrenergic categories were faintly stained for the AChE reaction after 5-15 min incubation and moderately stained after 30-60 min incubation at 0 degrees C. The present findings support the previous colorimetric data reported on the presence of AChE activity in the muscle. However, the typical cholinergic axons observed at the ultrastructural level did not show a heavy enough AChE activity to suggest their cholinergic nature.