Histomorphological study of the muscle content of esophagus in Persian leopard (Panthera pardus saxicolor)

The esophagus is a part of the digestive tube which has role in transferring of food from oral cavity to stomach. The musculature of the esophagus causes its movement. The muscle content of the esophagus has been studied in different species and showed notable differences. The information about muscle content in wild species is scant. Therefore, two Persian leopards were used in this investigation. After euthanizing, esophagus of each animal was removed. The samples were fixed in 10 % neutral buffered formalin. The tissues were routinely processed for light microscopy and embedded in paraffin. The paraffin blocks were cut into 5-7 µm sections and stained by hematoxylin-eosin and masson’s trichrome. The results showed that muscularis mucosa which made up of a smooth muscle was appeared from the caudal half of the esophagus as scattered fibers and became gradually thicken toward the caudal part of the esophagus. Tunica muscularis with internal circular and external longitudinal muscle layers which were separated with connective tissue have been seen in the beginning of esophagus. From the beginning of the second half of the esophagus, smooth muscle fibers were observed between the internal circular striated muscles and then gradually increased to be completely substituted with smooth muscle in caudal fourth part of the esophagus. Finally, in gastroesophageal junction, the longitudinal muscle was also substituted with smooth muscle and the smooth muscle of the esophagus continued to the stomach. This study is the first description of the histomorphological features of the esophagus of the leopard showed noticeable differences in type and arrangement of muscles within esophageal wall of this species in comparison with that of other mammals.