Glandular Epithelium PDF

Glandular epithelium  Learning objectives 1. Describe the Classification of glandular epithelium 2. Describe the mechanism of excretion of Exocrine glands 3. Describe the mechanism of excretion of Endocrine glands 4. Describe some Clinical application concerned with grandular epithelium  Gla...

Glandular epithelium  Learning objectives 1. Describe the Classification of glandular epithelium 2. Describe the mechanism of excretion of Exocrine glands 3. Describe the mechanism of excretion of Endocrine glands 4. Describe some Clinical application concerned with grandular epithelium  Glandular epithelium Formed by cells specialized secretory cells They are epithelial in origin Synthesize, store and secrete extracellular products Glands develop from covering epithelia  Glandular epithelium Exocrine glands; maintain connection with the surface epithelium via the tubular ducts Endocrine glands; are Ductless, release their secretory product (hormones) into the bloodstream  Exocrine Glands Unicellular Glands Multicelullar Glands  Classification 1. Shape and branch pattern of ducts - Simple (Unbranched ducts) - Compound (Branched ducts) 2. Mode of secretion - Merocrine - Apocerine - Holocrine 3.Nature of secretion - Serous - Mucous - Mixed (Seromucous)  Classification 1. Shape and branch pattern of ducts A. Duct portion Simple ducts not branched Compound - ducts with two or more branches  Classification B. Shape of the secretory portions Tubular – elongated long tube Acinar - rounded and saclike Tubuloacinar - mixed  Classification 2. Mechanism/Mode of secretion (A)Merocrine/Eccrine Secretory product is released by exocytosis = secretory granules leave the cell without any loss of cell substance; (e.g. pancreas, salivary glands  Classification (B) Apocrine secretion – the apical part of cytoplasm of the cells is lost together with the secretory product; (e.g. female mammary gland)  Classification (C) Holocrine secretion – breakdown and discharge of the entire secretory cell and its product; (e.g. sebaceous glands of the skin)  Nature of Secretions The nature of their secretions maybe serous glands, mucous glands, or mixed glands. – Serous: a nonviscous, watery fluid, such as sweat, milk, tears, or digestive juices – Mucous: mucin mixes with water to form mucus – Mixed: contain both serous and mucous secretions (seromucus)  Exocrine glands Secretory portions – releases secretory vesicles Excretory portion or ducts - transport the secretion out of the gland Supported by a stroma of connective tissue Form partitions or septa separating the gland into lobules  Endocrine Glands Ductless their connection with surface epithelium is lost during embryonic development their specific products – hormones are released directly into the bloodstream each epithelial cell of endocrine gland is in direct contact with blood capillary  Endocrine Glands Major morphological features of endocrine glands: – Ductless – Rich vascularization as well as innervation Special histological structure - 3 main types of endocrine glands: – Trabecular – Follicular – Disseminated  Endocrine Glands Trabecular type – made from the cords of the cells – e.g. adenohypophysis, parathyroid gland, adrenal glands  Endocrine Glands Follicular type – the cells form spherical structures – e.g. thyroid gland  Disseminated type Disseminated type exist in the mucosa of the digestive, respiratory and uro-genital tract as well as in the skin Occur either as single cells or in small clusters  Clinical application Adenocarcinoma - Malignant tumors derived from glandular epithelial tissue Adenocarcinomas are by far the most common tumors in adults after age 45. Acne - hair follicles become plugged with oil and dead skin cell  References Mescher AL Junqeira’s Basic histology 13th Edition Young B. et al Wheaters functional histology 5th edition Standring S. Grays Anatomy 39th Edition  The End Thank you