The majority of the ganglia of the vegetative nervous system are derivatives of the neural crest (NC) (ganglionic layer), a temporary formation consisting of cells which have migrated from the dorsal divisions of the closing neural tube [i, 7, 15, 17]. In addition to the neural ganglia, the melanocytes, the connective tissue formations of the heart, and several tissues of the head [13, 15], are also classed as derivatives of the NC.