The pontine micturition centres.

Objective: To review recent literature on the function of the two postulated pontine regions (the M- and L-regions) concerned with lower urinary tract control.

Material And Methods: The work reviewed is based on stimulation and lesion experiments and post-operative follow-up in the cat, supported by acute chemical stimulation and blocking experiments in the rat and PET functional brain scanning in humans.

Results And Conclusions: The M-region in the cat, homologous to Barrington's micturition centre and to a similar area in humans, is a small region both specific and necessary to voiding, the origin of the final common pathway to bladder and urethra, and the locus of co-ordination of the bladder and the striated sphincter. The L-region in the cat is part of a larger, less specific area that probably serves sphincter control in various circumstances, not exclusively micturition. The homolog of this region in the human or in the rat has not been adequately established.