The altrastructure of Auerbach's plexus in the guinea-pig. I. Neuronal elements.

The ultrastructural features of nerve cell bodies and axon profiles within Auerbach's plexus in the stomach, ileum, caecum and colon of the guinea-pig have been examined. Nerve cell bodies have been tentatively classified into nine different types according to their size, distribution of organelles, location and relationship to satellite cells. Except for cell size, no attempt has been made to correlate ultrastructual with light microscopical observations. On the basis of vesicular size, shape and content, eight morphologically distinct types of axon profile have been identified as well as two profile types which are thought to reflect different physiological conditions. The axons contained various populations of small, mostly granular vesicles; small, round agranular vesicles; small, flattened vesicles; large flattened or elongated vesicles; and three types of large vesicle with granular contents distinguished by size. Some correlation between types of axon profile and two types of nerve cell body was recognized. However, more than one type of axon profile usually formed synapses with one type of cell body, and a precise correlation was not determined.