Morphometric study of the microvasculature of the main excretory duct subepithelia of the rat parotid, submandibular and sublingual salivary glands.

This study investigated the relationship between the fine structure of the main excretory duct (MED) epithelia and the subepithelial capillaries of the major salivary glands (parotid, submandibular, and sublingual) in the rat. The MED subepithelial capillaries vary in type (fenestrated and continuous), number of fenestrae present in the available fenestrated endothelium (the attenuated area of endothelium), and number of capillaries per unit length of epithelium. In the parotid gland, continuous capillaries predominate, and the capillary density per 200 microns of epithelium (1.73 in region I and 1.03 in region II) is lower than in the other two glands, as is the number of fenestrae per 10 microns of available endothelium (1.97 in region I and 1.25 in region II). The submandibular gland has mainly fenestrated capillaries. The capillary density per 200 microns of epithelium (4.46 in region I and 5.51 in region II) is higher than in the other two glands, as is the number of fenestrae per 10 microns of available endothelium (4.82 in region I and 7.90 in region II). Similarly, in the sublingual gland, fenestrated capillaries are dominant. The density of capillaries per 200 microns of epithelium (4.15 in region I and 4.31 in region II) is intermediate between the parotid and submandibular glands, as is the number of fenestrae per 10 microns of available endothelium (2.98 in region I and 3.83 in region II).