Morphological Studies On The Component And Modulation Of The Pontine Micturition Reflex In The Rat And Rabbit

Barrington's nucleus that located in the pontine dorsolateral tegmentum is an important site for controlling voiding in the mammalian brain and is often referred to as pontine micturition center. Barrington's nucleus sends direct projection fibers to the sacral parasympathetic nucleus in which parasympathetic preganglionic neurons innervating detrusor muscles of the bladder are distributed. Electron or chemical stimulation of Barrington's nucleus clicits bladder contraction and increases discharges of bladder postganglionic nerve. Conversely, lesion of the nucleus results in a permanent inability to empty the bladder. On the other hand, an area located just ventral to Barrington's nucleu has been reported to send projection fibers to the ventrolateral group of Onuf's nucleus in the caudal lumbar cord segments; the vetrolateral group of Onuf s nucleus is mainly composed of pudendal motor neurons innervating the external urethral sphincter muscle. Therefore, D-regions may be considered as pontine storage center as compared with Barrington's nucleus (pontine micturition center). At the present, however, it is still unclear about how the bladder-filling information is conveyed to Barrington's nucleus and/or D-region. Therefore, morphological experiments...