Sexual dimorphism of pleopod motor neurons in lobster

Sexual dimorphism of the efferent neurons that innervate the pleopods in the first abdominal segment of the lobster was examined with nickel/cobalt backfilling techniques. An average of 28.8 somata (maximum of 31) were stained in the female while the mean number of male efferent somata was 25.8 (maximum of 28). These differences are statistically significant. All except one of these somata are situated close to the base of the ipsilateral first root. They are organized into large anterior (13-21 somata) and small posterior (8-13) clusters. One soma is located on the contralateral side of the ganglion.