Abstract
1. The terminal portion of the mandibular gland of the rabbit belongs to the compound tubulo-acinous gland. The tubular portion is a continuation of the intercalated portion, mainly consisting of dark cells (granular cells of KRAUSE). The aciuous portion at the tail is composed of light cells (chief cells of GOTO), which show faveolate structure.
2. The granular cells and the chief cells repeat the secretion function in their own ways. Accordingly, the secreta of the mandibular gland of rabbit is at least a mixture of the two.
3. The granules in the granular cells arise from fine granules originated from mitochondria. They are distinguished as such by having a membrane around them in the electron microscope. Loosing the stainability transform the granules into vacuoles and are emitted into the gland lumen, but sometimes, granules are discharged into the lumen without any substantial changes.
4. The faveolate structure of the chief cells is due to vacuoles filling up the cytoplasm. The substance in the vacuoles is stained extremely light. It is considered that the endoplasmic reticulum has something to do with the formation of the vacuoles.
5. As for the differentiation of the granular cells, they show a typical structure in certain embryonic stage and begins to discharge the granules after birth, but in the weaning period, the function falls off.
6. The differentiation of the chief cells begins later. They develop after the end of the embryonic stage, but only in the weaning stage starts the discharge of vacuole substance. The chief ingredient of the secreta is then the production from the chief cells.
