Fine structure of the rabbit submandibular gland during the embryonic development.

The development of the submandibular gland has been examined in rabbit embryos from the 22nd day to the birth. The 2 main types of secretory cells, which synthetize dense serous granules or large pale mucous granules can be identified from the 24th day of development. A third type of cells, characterized by granules having different densities, has been identified in the preterminal tracts. The possibility that these cells are similar to some small cell with an highly dilated endoplasmic reticulum found in adult rabbit submandibular glands is discussed.