Structure and function in the third abdominal ganglion of the crayfish Procambarus clarkii (Girard)

The functional anatomy of the crayfish third abdominal ganglion was explored by reconstructions from silver‐stained serial sections and by intracellular recording from units in the neuropile. Fibers entering the ganglion from the ventral nerve cord and the peripheral nerves from bundales with different paths and destinations. These bundles and other anatomical features such as commissures and cell body groups are constant from animal to animal, as are the positions of individual fibers and their branches. Organization in the ganglion is not based on topographical representation of the periphery, but there is a relation between the functions of individual fibers and their positions. Some of the bundles consist of fibers with similar or related functions. The orderliness, constancy and functional relations of the anatomy point toward specific anatomical connectivity between fibers in this preparation.