The ultrastructure of the neural plexus in the foot musculature of the desert snail Eremina ehrenbergi.

The foot of the desert snail, Eremina ehrenbergi, is supplied by branches of the pedal nerves which enter a coarse-meshed peripheral neural plexus. Light and electron microscopic preparations revealed the presence of ganglionic knots embedded in the foot musculature. In these knots the neural cell bodies are found to be situated on the periphery of neuropile. Cross sections through the neuropile demonstrate the presence of many synaptic junctions of the axo-axonic type. In some axon profiles light and dense synaptic vesicles are observed. Some of the axons which constitute the terminal plexus enter into close apposition with muscle cells and definite areas where synaptic transmission in thought to occur are well observed. On the basis of these results it can be concluded that the neural plexus may be involved in the production of the patterned pedal activity in Eremina ehrenbergi.