PRACTICAL ROADMAP GLANDS Mrs. A. Jovanović Unicellular Glands Multicellular Unicellular gland –Goblet cell Multicellular gland Simple tubular Simple Simple alveolar Simple tubulo‐alveolar Multicellular glands Compound tubular Compound Compound alveolar Compound tubulo‐alveolar MULTICELLULAR GLANDS Simple Simple tubular (Simple coiled tubular) Simple alveolar (Simple branched alveolar) Simple tubulo‐alveolar SIMPLE GLANDS • Slide 85 Jejunum Simple tubular gland Unicellular gland ‐ Goblet cell Plica circulares Lumen of jejunum Wall of jejunum Plica circulares Villus (singular) Villi (plural) Glands Simple tubular glands are labelled with a black arrow. Note how they open in between two adjacent villi. You can clearly see their one unbranched simple duct (D) and a tubular (tube shaped) secretory end piece (SE). Lumen The encircled structure is the secretory and piece of a gland cut in a cross section. The other glands have been cut longitudinally which is the reason you see both the ducts as well as secretory end pieces. The inset shows pale goblet cells labelled with a black arrow. SIMPLE GLANDS • Slide 91 Colon Simple tubular gland Unicellular gland –Goblet cell Wall of the colon Lumen Glands Mucosa Mucosa Simple tubular glands Simple tubular gland is encircled in black. The dominant goblet cells constitute the glandular epithelium. Simple columnar epithelial cells with a microvillus border are present but not often visible in between the goblet cells. The simple duct of the gland delivers mucous secretion (labelled with black arrows) onto the luminal surface. Lumen SIMPLE GLANDS • Slide 10 Uterus Simple tubular gland Lumen Simple tubular glands Stroma Lumen Blood vessels Simple tubular glands SIMPLE GLANDS • Slide 36 Thin skin Sebaceous gland ‐ Simple branched alveolar gland Eccrine sweat gland ‐ Simple coiled tubular gland Hair follicle Sebaceous gland Hypodermis Eccrine sweat gland Dermis Epidermis Sebaceous gland Note: This gland is only present in the thin skin since it is found associated with a hair follicle. The thick skin found on the soles of our feet and palms of our hands is hairless skin and thus has no sebaceous glands! Sebaceous gland Note: Sebaceous gland is associated with a hair follicle. This simple (one duct labelled with a black arrow) branched alveolar (secretory end pieces branched and sack like – encircled) gland delivers its waxy secretion called sebum into the hair follicle, coating the hair and providing lubrication. Note: Each cell of this gland undergoes programmed cell death after the sebum has been released into the hair follicle (holocrine mode of secretion). The cells of this gland are often confused with mucous cells, thus please note the shape of the cells in the sebaceous gland and position of the nucleus and compare those with the cells of the mucous secreting gland (goblet cell or submandibular gland)! Smooth muscle • Eccrine sweat gland This simple gland is present in both thick and thin skin (we sweat on our palms and soles as well as on our scalp!) Eccrine sweat gland Duct of the eccrine sweat gland leading to the skin surface Hair follicle The secretory end piece of the eccrine sweat gland is made out of the simple cuboidal epithelium or sometimes pseudostratified epithelium (encircled in black). Note the cuboidal cell shape and centrally placed round nucleus present in the encircled structure). The ducts of the eccrine sweat gland (encircled in red) are made out of the stratified cuboidal epithelial cells since they have more than one layer of epithelial cells. Note the presence of two layers of cells in the duct sections and the proximity of dark nuclei is the reason the ducts stain more basophilically. SIMPLE GLANDS • Slide 35 Thick skin Eccrine sweat gland Note: Eccrine sweat gland is present in both thin and thick skin. The duct of the eccrine sweat gland “traveling” through the epidermis of the thick skin Ducts Secretory end pieces The ducts with stratified cuboidal epithelium The secretory end piece with simple cuboidal or pseudostratified epithelial cells MALTICELLULAR GLANDS Compound Compound tubular Compound alveolar Compound tubulo‐alveolar MULTICELLULAR GLANDS • Slide 2 Submandibular gland Compound tubulo‐alveolar gland Connective tissue capsule Tissue parenchyma Connective tissue septa Interlobular duct Tissue parenchyma consists of both mucous (labelled with red arrows) and serous (labelled with black arrows) regions thus the gland is classified as mixed according to its nature of secretion Intralobular striated ducts Note the the presence of many intralobular ducts (black arrows) within connective tissue septae. These ducts are lined with stratified epithelial cells and surrounded with eosinophilically staining connective tissue Striated intralobular duct Intercalated intralobular ducts Striations Striated duct (intralobular duct Serous secretory end Mucous secretory piece end piece Note the difference between tubular mucous (blue tube) and pyramidal serous (black pyramid) secreting cells of the respective secretory end pieces. Also note the staining of the cell, position and shape of the nucleus. Note contractile myoepithelial cells (black arrow) located in between the basal plasma membrane of the secretory epithelial cells and the basement membrane. Their function is the move secretion towards the excretory duct.