RESUMEN
This study was undertaken to determine the anatomical characters of the lower esophageal segment [LES] in man and to establish a correlation between these anatomical features and their physiological properties. Manometric studies of LES were performed in 25 normal volunteers. The end expiratory fundic pressure was taken as zero reference and all values were expressed in mm Hg. The manometric characteristics of the lower esophageal segment were determined. The LES length was measured and divided into four equal quarters. Upper gastro-intestinal endoscopy was performed in 12 normal volunteers using Olympus gastrointestinal fibroptic endoscope GIF-K2 type. Twenty-one human specimens were used for gross anatomical studies of muscular thickness and architecture of the LES using microdissection techniques. For histological examination, 22 adult normal human specimens were used; 10 for longitudinal and 12 for transverse sections. . They were proceeded for paraffin sections and stained with haematoxylin and eosin and Verhoeff's stains. Endoscopic examination showed a sharp line of demarcation between the pinkish mucosa of the stomach and the grayish mucosa of the esophagus. Manometric study showed a higher pressure zone at the LES of the esophagus. The length of this high pressure zone is variable from subject from subject to another. There is an axial asymmetry in the pressure of LES. The pressure is higher in the middle two quarters of the LES than the cranial and caudal quarters. Microdissection and histological techniques showed asymmetry in the thickness of the inner circular muscle layer of the LES. The area of maximum thickness is considered as the gastro-es0phageal ring [GER]. The thickness of the circular muscle layer is tapered above and below the GER i.e there is axial asymmetry. The degree of thickness of the circular muscle layer is variable in relation to the different Walls of the the LES i.e there is radial asymmetry. There was close correlation between manometric records and muscular thickness in the LES. The area of maximum pressure in the middle part of LES coincided with the area of highest thickness of the inner circular muscle layer at the gastroesophageal ring [GER]. The extent of this muscular thickness is equal to the length of the high pressure zone. The lower esophageal sphincter is not a ring sphincter due to the presence of radial asymmetry in the circular muscle layer. In addition, there is an axial asymmetry in the thickness of inner circular muscle layer. The asymmetric muscular thickening at the gastro-esophageal junction is mirrored in the manometric images of the lower esophageal high pressure zone. Manometric assessment of the lower esophageat segment, therefore, reflects muscular structure and architecture of the human gastro-esophageal junction