Distribution of Mast cells and Nerves in the Developing Postnatal Submandibular and Sublingual Glands of Rats

The distribution of mast cells and nerves were investigated in the submandibular and sublingual glands of postnatal rats, using morphometric, histochemical and immunohistochemical techniques. Mast cells were observed in the submandibular and sublingual glands of postnatal development. Number of mast cells gradually increased in both glands following development. At birth, mast cells were relatively fewer in submandibular gland than those in sublingual gland, and they were mainly distributed in parenchymal tissues. At weeks, most of the mast cells were observed in the connective tissues, surrounding neurovascular elements, but some mast cells were closely related with the acini of submandibular gland. PGP 9.5 immunoreactive nerve fibers were found in the submandibular and sublingual glands of all developmental age. The nerve fibers were showed in varicose shape, and mainly located in adjacent area of ducts and vascular components of both glands. The number of nerve fibers were increased rapidly until 8 weeks, but they were not increased any more until 24 weeks. Therefore, it is suggested that mast cells and nerve fibers related with each other, and that their interactions may play roles not only in maturation of secretory units but also growth and differentiation of the tubular structures of the rat submandibular and sublingual glands during postnatal development.