Effect of glucocorticoid on the differentiation and development of terminal tubules in the fetal rat submandibular gland.

Glucocorticoids (CORT) are known to promote branching of the epithelial cords during the development of the rat submandibular gland. The aim of this study was to examine the effect of CORT (triamcinolone) on the differentiation of cells forming the terminal tubules in the developing fetal rat submandibular gland and the properties of the secretory granules. Light and electron microscopy showed that the terminal tubules of the glands in the experimental group contained more type III cells, which have been identified as proacinar cells, than those in the control group, whereas the relative number of type I cells, which have been identified as terminal tubule cells, was reduced. Immunoelectron microscopy using an antibody against neonatal submandibular gland secretory protein B (SMGB) revealed the presence of more gold particles over type III cell granules in the experimental group than in the control group. Lectin histochemistry demonstrated more wheat germ agglutinin (WGA)-labeled gold particles over type III cell granules in the experimental group than in the control group. These findings suggest that CORT promote the differentiation of type III cells, and moreover stimulate the production of secretory granules reactive for SMGB and WGA by acting on the terminal tubules of the developing rat submandibular gland.

The internal structure of bony tissue of a human metopic suture by Soft X-ray.

A complete metopic suture was found in the frontal bone of a 79 years old male cadaver. Compact bone matrices were found in the border region of the metopic suture using a Soft X-ray apparatus. The coronal and sagittal sutures were also complete. The appearance of these complete cranial sutures may be due to continuous bone restructuring and resorption in the border region of sutures during brain development of brachy crany.