Esophagus

The oral cavity and the esophagus are lined by stratified squamous epithelium. In which animals might we expect it to be keratinized, and in which might we expect non-keratinized? Why? Tie the structure to the function and remind yourself why this is so.

The tunica muscularis of the esophagus in ruminants and dogs consists entirely of skeletal muscle, while in the horse, pig and cat, the distal 2/3 or more consists of smooth muscle. Why is it entirely skeletal muscle in ruminants and in the dog?

In Virtual Microscopy, the esophagus is on the right, trachea on the left. [WebSlide] Respiratory_WSU; Trachea,Esophagus (WSU_2_069a)