Central regulation of the pharyngeal and upper esophageal reflexes during swallowing in the Japanese eel.

We investigated the regulation of the pharyngeal and upper esophageal reflexes during swallowing in eel. By retrograde tracing from the muscles, the motoneurons of the upper esophageal sphincter (UES) were located caudally within the mid-region of the glossopharyngeal-vagal motor complex (mGVC). In contrast, the motoneurons innervating the pharyngeal wall were localized medially within mGVC. Sensory pharyngeal fibers in the vagal nerve terminated in the caudal region of the viscerosensory column (cVSC). Using the isolated brain, we recorded 51 spontaneously active neurons within mGVC. These neurons could be divided into rhythmically (n = 8) and continuously (n = 43) firing units. The rhythmically firing neurons seemed to be restricted medially, whereas the continuously firing neurons were found caudally within mGVC. The rhythmically firing neurons were activated by the stimulation of the cVSC. In contrast, the stimulation of the cVSC inhibited firing of most, but not all the continuously firing neurons. The inhibitory effect was blocked by prazosin in 17 out of 38 neurons. Yohimbine also blocked the cVSC-induced inhibition in five of prazosin-sensitive neurons. We suggest that the neurons in cVSC inhibit the continuously firing motoneurons to relax the UES and stimulate the rhythmically firing neurons to constrict the pharynx simultaneously.

The normal anatomy around the oesophagogastric junction: a histopathologic view and its correlation with endoscopy.

The incidence of primary oesophageal adenocarcinoma in Caucasian men has recently been increasing rapidly. Therefore, primary oesophageal adenocarcinoma, columnar-lined oesophagus (CLO) or Barrett's oesophagus and the normal condition of the lower segment of the oesophagus are currently receiving worldwide attention in the medical field. Precise definitions of the anatomical features of the oesophagogastric junction (OGJ) are essential before accurate assessment of CLO can be made. This article reviews the normal morphological features in the OGJ zone to give a closer insight into the histopathology and endoscopic appearance of the OGJ and CLO. We review definitions of the OGJ, the pattern of the squamocolumnar junction (SCJ), oesophageal cardiac-type glands beneath the squamous epithelium, the normal squamous epithelium, columnar islands in squamous-lined mucosa, squamous islands in CLO and newly reported metaplastic changes in the OGJ zone. The nature of the OGJ is clarified in detail through comparison between endoscopically evident and histological features.