Journal of the autonomic nervous system
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J. Auton. Nerv. Syst. · Apr 1981
Organization of the sacral parasympathetic reflex pathways to the urinary bladder and large intestine.
Electrophysiological and horseradish peroxidase (HRP) techniques have provided new insights into the organization of the sacral parasympathetic reflex pathways to the large intestine and urinary bladder. The innervation of the two organs arises from separate groups of sacral preganglionic cells: (1) a dorsal band of cells in laminae V and VI providing an input to the intestine; and (2) a lateral band of cells in lamina VII providing an input to the bladder. These two groups of cells were separated by an interband region containing tract cells and interneurons. ⋯ The long latency is attributable to the slow conduction velocity in immature unmyelinated peripheral and central axons. In chronic spinal kittens (3-7 days after spinalization) the long latency reflex was abolished and a shorter latency (90-150 msec) bladder reflex was unmasked. The emergence of this spinal pathway may reflect axonal sprouting and the formation of new reflex connections within the sacral parasympathetic nucleus.
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The anatomical and functional organization of cardiac vagal preganglionic somata and the organization of ascending spinal pathways regulating the cell bodies were studies in the dog and cat. Horseradish peroxidase was injected subepicardially in cats after left or right cervical vagotomy to retrogradely label cardiomotor neurons. Somata were ipsilateral to the intact vagus in the dorsal motor nucleus (DMN) of the vagus, the nucleus ambiguus (NA) and an intermediate zone (IZ) between the DMN and NA. ⋯ Bilateral lesions placed in the dorsolateral sulcus area abolished the effects of somatic afferent stimulation. Thus, an ascending pathway regulating somata of the DMN and NA is located bilaterally in the dorsolateral sulcus. Similar studies in the dog suggested the pathway extends into the dorsolateral funiculus as well.