The membrane of the cardiac portion is uniformly smooth; that of the pyloric is thicker and more vascular."
"Sketches of the Natural History of Ceylon"
J. Emerson Tennent
The circular layer becomes quite thick at the pyloric orifice, forming a distinct band which serves as a valve.
"Physiology and Hygiene for Secondary Schools"
Francis M. Walters, A.M.
After the discharge the pyloric muscle again contracts, and so remains until the time arrives for another discharge.
"Physiology and Hygiene for Secondary Schools"
Francis M. Walters, A.M.