PS 15 - Salivary Gland (MS 44 4X, H&E) This PS shows many lobules of varying sizes. The LCT septa are evident between the lobules with some large ducts and blood vessels evident. Salivary glands are outpocketings of ORAL ECTODERM. They are branching tubular or tubulo- acinar glands and according to their method of secretion, are called merocrine. The physiochemical nature of their secretory products are: SEROUS - a non-viscous watery type secretion which usually contains an enzyme, and MUCOUS - a secretion that is more viscous than the serous type and used mainly as a lubricant or gland may contain both types which is referred to a mixed type gland. These glands have a rich blood supply and a capsule of loose to dense connective tissue. The connective tissue around the lobules is generally LCT with many fibroblasts, fibrocytes, and macrophages. Also, you may find plasma cells. The following list is a brief description of morphological features of a salivary gland: 1. SEROUS ACINUS - on a comparative basis, these cells stain darker than the mucous cells. On H&E stain, the cytoplasm appears pink to lavender in color. The nucleus is round and towards the basal end, but not on the basal end. 2. MUCOUS ACINUS - these stain lighter than the serous glands. The cytoplasm appears foamy. The nucleus is flattened and on the basal end. 3. MIXED GLAND - contains both types of cells and sometimes a serous component called a serous demilune. 4. INTERCALATED DUCTS - made of low cuboidal cells. Arise or terminate in a terminal acinus (end piece). 5. INTRALOBULAR DUCT - these ducts are also called salivary or striated ducts. These ducts are lined by columnar epithelium and are continuous with the intercalated ducts. Surrounded by the parenchymal (secretory) cells. 6. INTERLOBULAR DUCT - the epithelium of these ducts are columnar, to stratified cuboidal, to stratified columnar, to pseudostratified columnar epithelium. These ducts are surrounded by connective tissue. 7. MYOEPITHELIAL CELL - also called a basket cell and often referred to as a modified smooth muscle cell. It is a small dark structure that closely invests the secretory end piece (acinus). It aids in expelling the secretory product by contracting or squeezing the acinus. 8. SEROUS DEMILUNE - half-moon shaped structure composed of serous cells projecting to one side of a mucous end piece. .