Ampulla in the main excretory duct of the mouse submandibular gland. Histological and three dimensional examination.

An ampulla was found in the main excretory duct (MED) of a mouse submandibular gland. The major aim of the present study was to examine the structure of this ampulla and to consider its functional characteristics. The MED was cut together with the lower jaw and studied by light and electron microscopy, and with a computer system to determine its three-dimensional structure. The ampulla was formed as a part of the MED within the submucosa of the floor of the oral cavity close to the caruncula sublingualis. The ampulla had a pseudostratified epithelium composed of light, dark and basal cells. The anterior wall of the ampulla was in contact with the mandible, and the lateral, medial, inferior and posterior walls were surrounded by striated muscle fibers from the suprahyoid muscle.These findings suggest that the ampulla temporarily stores saliva, modifies its composition, and then excretes it in response to demand.