Observations on the movements and structure of the bursa of Nippostrongylus brasiliensis and Nematospiroides dubius

Abstract

There is growing evidence of the autonomy of the movements of certain organ systems in nematodes. The copulatory bursa of male strongylines is believed to aid in mating, although there arc very few reports of this. Furthermore, it has been suggested that movements of the bursa are stimulated by a pheromone secreted by the female. Bursal movements were investigated with respect to these themes and the fine structure of the bursa of Nippostrongylus brasiliensis was examined. When the bursa was ligatured and isolated from the body, bursal movements of N. brasiliensis and Nematospiroides dubius were greatly increased for extended periods. The movements showed rhythmic pacemaker activity and they simulated the movements observed in the normal mating of N. dubius. The bursa of N. brasiliensis was found to have muscular and sensory elements, a nerve was shown to be present in both spicules, and sensory elements were located in the genital cone. The increase in movements is believed to result from the removal of an inhibitor associated with the circumpharyngeal commissure. These results are discussed in terms of other observations on control mechanisms in nematodes and their functional morphology.