Glandular Epithelia
By Rasha Mohamad Shaker • Gland: Single cell or group of cells, derived from epithelia, secrete substances into ducts, onto a surface or into the blood.
• Glandular Epithelium is a type of epithelial tissue formed by cells specialized to produce secretion. • Glands
Exocrine glands Endocrine glands
Unicellular glands Multicellular glands (goblet cell)
Simple Compound Simple Alveolar Compound Alveolar
Simple Branched Alveolar Simple tubular Simple Branched Compound Tubular Tubular Simple Coiled Tubular Compound Tubuloalveolar •Classification of glands: • Glands are generally classified into two major groups according to the presence or absence of duct in to : • Exocrine glands • Composed from secretory units and duct systems , release their products onto an epithelial surface, either directly or through a duct e.g; salivary glands. • Endocrine glands • These are ductless and their secretion is carried directly to their site of action by the blood stream e.g: Thyroid gland • Mixed variety • Some glands possess both exocrine and endocrine function e.g; pancreas and liver. Classification of Exocrine Glands
The glands in this group can be divided according to number of cells in to:
Types of glands Description Example Unicellular glands formed of a single cell Goblet cell
Multicellular glands formed of numerous salivary glands cells Multicellular Exocrine Gland • Exocrine glands contain a secretory portion and a duct portion
• The duct portion may be : • compound have branched secretory parts • simple unbranched secretory parts • The secretory portion may be: • tubular have tubular secretory parts • alveolar (flask shaped) or acinar (grape like) secretory parts • Tubuloalveolar mix of the two Multicellular Exocrine Glands classification 1)Structural classification 2) Type of secretion
Type Description serous composed of serous cells which are pyramidal cells arranged around a small scarcely visible lumen. These cells show a small round nucleus located in the basal zone of deeply basophilic cytoplasm and a lighter apical portion. secretory (zymogen ) granules are seen in the apical area. Mucous larger than serous alveoli and more variable in size and shape They are composed of often more columnar form of mucous cells, with pale oval or flattened nuclei at the bases of the cells and larger more apparent lumen. mixed contain serous and mucous separately or mucous surrounded by part of serous thick, lipid rich secretions of cuboidal cells in certain skin sebaceous regions
3) According to method (mode) of secretion secretion Type of glands Description Example
Merocrine the secretory cells are not salivary glands destroyed during secretion
Apocrine the apical part of the cells Mammary glands is destroyed during secretion.
Holocrine the whole cell is destroyed Sebaceous (oil) gland during secretion e.g. sebaceous glands. • Salivary Glands
*Salivary Glands include the parotid, submandibular and sublingual glands
*the salivary glands are composed of serous cells and mucous cells.
*The parotid glands contain only serous cells in the form of serous alveoli
*The submandibular glands are mixed glands (serous and mucous ) *The sublingual glands are also mixed glands • Sweat Glands : • Sweat gland is a simple coiled tubular gland. • the secretory part lies coiled in while the duct extends to open in a funnel shaped in the skin surface • Oil glands • they are simple alveolar glands found all over the body except on palms and soles. The oil glands secrete an oily secretion called (sebum), which is usually secreted hair follicle.