The physiology and anatomy of the esophagus of normal llamas and llamas with megaesophagus.

摘要

Solid-state esophageal manometry was used to study physiology of the normal llama esophagus. Esophageal baseline pressures, esophageal response to water swallows and to balloon distention, and other motor activity of the esophagus during experiments were measured throughout the entire length of the esophagus. Gross and histologic anatomy, muscle fiber type classification, and ultrastructural morphology were used to study anatomy of the normal llama esophagus. The methods as described were also applied to study the physiology and anatomy of two llamas with megaesophagus and one llama with esophageal motor abnormalities.; Primary peristalsis in response to a water swallow is unique in the llama esophagus. Duration of contraction is very short. Propagation velocity of the peristaltic wave is fast, approximately ten times of that of the human. Amplitude of contraction and mean rate of pressure change per unit time are the greatest in the pharyngoesophageal region and the lowest in the lower esophageal sphincter region. Length of the cervical portion of the esophagus is almost twice that of the thoracic portion in keeping with long neck. Submucosal glands are abundant throughout the esophagus. Type 2 muscle fibers are predominant throughout the esophagus. Type 1 muscle fibers are also present and gradually increase in the distal portion of the esophagus. Generally, ultrastructure of the striated muscle of the esophagus is similar to that of the skeletal muscle.; Primary peristalsis was abnormal in llamas with megaesophagus. More than a half of the distal esophagus was aperistaltic. Manometric findings corresponded to anatomical findings. Esophageal dilation was remarkable in the distal portion of the esophagus. Evidence of denervation atrophy of the esophageal striated muscle was not found in the cranial cervical region, but was found in the middle cervical region through the distal thoracic region.; This study provides extensive normal data on the llama esophagus to serve as a baseline for further study of esophageal pathology in the llama. Findings from this study suggest that denervating disease is a cause of megaesophagus in the llama, although the exact nature of this disease is still unknown.