Vascularization of the crayfish abdominal nerve cord

Abstract

The anatomy of the vascular supply to the abdominal nerve cord of the crayfishProcambarus clarkii was investigated by filling the arterial supply with ink injected into the heart. The abdominal nerve cord was found to receive all of its blood supply from the ventral artery, which parallels the ventral midline of the nerve cord. Extensive vascularization of the abdominal nerve cord was revealed, with more major arterial inputs entering the ganglia than the connectives (Figs. 2, 3, 6). Both the neuronal somata and the neuropil are heavily vascularized (Figs. 4, 6). The connectives contained little of the fine vascularization found within the ganglia, and the roots were lightly and variably vascularized (Figs. 5, 6). Cannulation of the arterial supply can be used to deliver solutions to synapses within the ganglionic neuropil (Figs. 7, 8). Responses of the lateral giant axon (LG) to root and cord stimuli were used to monitor the effects of ionic substitutions in the bathing medium and arterial perfusate. Polysynaptic pathways containing chemical synapses were unaffected when the bathing medium was high Mg++, low Ca++ saline and the arterial perfusate was normal saline. These same pathways were blocked rapidly by arterial perfusion of high Mg++, low Ca++ saline.