*1.3.3 Serous glands*

*Chronic Autoimmune Epithelitis - Sjogren's Syndrome and Other Autoimmune Diseases...*

The cover epithelium lines up the outer surface of the body and the inner surface of the hollow organs. The multilayer squamous epithelium, which forms the epidermis of the skin, has a protective effect by covering the outer surface of the body. Under the epithelium, there is a lamina propria and they are called as mucosa together and cover the inner surface of the cavities. Structures such as nasal mucosa, airway mucosa, digestive system mucosa, and urinary tract mucosa are good examples of laying lumen structures related to epithelial tissue [4–8].

a.The endocrine (hormone-producing) glands include the Langerhans islets of the pancreas, adrenal glands, and thyroid and parathyroid glands. Endocrine glands are supported by reticular fibers, arranged in cord or follicle. The most common cord shape is seen in the form of anastomoses around the capillaries or blood sinusoids. The produced hormone in the cell (adrenal gland, anterior lobe of the pituitary gland, parathyroid gland) is released through the appro-

priate signaling molecule or neural stimulus. In the follicular form of

tions to the capillary network of the surrounding area [4].

the endocrine gland, secretory cells surround the follicular cavity and store the produced hormone. The best example of this is the thyroid gland. Therefore, the endocrine glands do not have a discharge channel and deliver their secre-

b.Exocrine glands give their secretions to the external environment via a duct channel and are not rich in capillary network. Part of the pancreas, parotid, submandibular, and sublingual glands are the examples of exocrine glands [4–6, 8, 10].

There are irregular tight connective tissue sheath around the macroscopic glands

which are parotid, submandibular, and sublingual gland. The connective tissue enters into the glands in the form of septa. The septa divide the gland into compartments. In the compartments, there may be acinus or tubules or both according to the type of the gland. Intralobulated duct channels are also included within the lobule. In the septa of connective tissue, interlobular channels are located. From these visible glands, the serous glands consist of acinus (alveolus), and the mucous glands are mucous tubules (**Figure 11a**–**d**). Exocrine glands can be subdivided into serous, mucous, and mixed glands according to the nature of the secretion they produce. Both serous- and mucous-secreting endpieces are covered with cubic epithelial cells which form intercalated (initial) ducts. Intercalated ducts combine to form the striated (intralobular) ducts. The intralobular ducts merge together to form the interlobular duct. These ducts are joined together and form "Stenson" in the parotid gland, "Wharton" in the submandibular gland, and "major sublingual" channels in the sublingual gland and open into the oral cavity. The most important features of intralobular ducts are the membrane folds extending from the cell basal to the nuclei. A large number of mitochondria were placed on the long axis of these folds. Such a location is particularly important for the salivary gland, which is functionally intense and consumes relatively more energy during its work. The parotid and the exocrine glands part of the pancreas are pure serous. The submandibular and

**1.3 Epithelium is classified as cover and secretory epithelium**

There are two types of glands—endocrine and exocrine.

*1.3.1 Cover epithelium*

*1.3.2 Secretory epithelium*

**20**

sublingual glands are mixed glands [4–9].

The abundant zymogen granules in the serous glands are found in the upper part of the cell cytoplasm. Serous glands produce a smooth flow and protein secretion. The duct channels are narrower than the mucous glands. The nuclei of the cells are located in the middle and are round in shape. In the sections stained with hematoxylin–eosin, the basal part of the cell is stained with hematoxylin, and the apical portion is stained with eosin [4–8, 10] (**Figure 11c**).
