[Structure of the esophagus of the dog]

The structure and arrangement of muscle fibres and vessels in various parts of the esophagus was investigated in 22 dogs using light and scanning electron microscopical techniques. The esophageal muscularis propria does not consist of outer longitudinal and inner circular fibres but of two layers of skeletal muscles forming apolar screw-like fascicles that run in opposite directions. Sphincter-like muscle fibre bundles in the upper cervical and abdominal part are closely connected with the tubular part of the esophagus. The present morphological findings indicate that the esophagus of the dog should not be considered to be a useful model for the elucidation of human esophageal malfunctions and their therapy.