7. Basal, Glands Flashcards
Significantly increase the surface area of the basal domain • Allow for more transport proteins and channels to be present • Well developed in cells performing active transport of molecules
- Kidney tubule
- Striated ducts of exocrine glands
• Mitochondria arranged vertically in these folds
• Light microscopy - “striated” appearance
Basal Infoldings
An electron dense area found between the basal surface of the epithelial cells and the adjacent connective tissue
• Because of this, is also called lamina densa
• About 40-60 nm thick • Contains a network of filament (3-4 nm
long) called laminins • Also rich in type IV collagen, proteoglycans and glycoproteins • Forms the structural attachment site for overlying epithelial cells and the underlying connective tissue (fibroreticular lamina)
Basal Lamina
Structural attachment – anchors cells to the underlying connective
tissue
• Compartmentalization – separate the epithelia from the connective tissue
• Filtration – regulate the movement of ions and molecules between the epithelial cell and the connective tissue
• Tissue scaffolding – during regeneration, the newly formed cells use the remaining basal lamina as a guide to create the cells in their original form
• Cell regulation and signaling – molecules within the basal lamina interact with cell surface molecules of cells in the connective tissue that guide wound healing, cell shape etc.
Functions of a basal lamina
Can be visualized with the light microscope
• Amorphous layer at basal surface of epithelia
• Especially thick in respiratory epithelium
• Composed of Basal Lamina and Reticular/Fibroreticular lamina
• The reticular lamina is rich in type III collagen
Basement Membrane
Trachea and Kidney basement membrane
More H&E and PAS of Basement Membranes
• One or more cells, mostly epithelial cells
• Secrete substances directly into the blood stream or through a conduit onto surfaces/cavities
Glands
One of two major gland groups based on how they secrete their products.
Secrete into blood vessels or extracellular space via the process of exocytosis
• Known as “ductless”
Secrete their products (hormones) into the connective tissue which then enters the bloodstream.
Endocrine
One of two major gland groups based on how they secrete their products.
Secretes into ducts that connects to the surface of the cell or to body cavities (ex. Saliva, sweat)
Exocrine
Endocrine glands
Mode of secretion
Onto Nearby Cells
Paracrine
Endocrine Glands
Mode of secretion
Onto same cell
Autocrine
Endocrine Glands (picture)
Pituitary, adrenal, thyroid
Exocrine Gland Classification (One of two types)
Single cell that secretes directly onto the surface or cavity.
Mode of secretion is mainly exocytosis.
Unicellular
Ex. Goblet Cells: Secretes mucus that protects and lubricates.
Exocrine Gland Classification (One of two types)
• Multiple cells that work together to secrete and transport their product through a duct on the
epithelial surface/cavity
• Have two main portions
• an epithelium-derived part that forms a duct/excretory portion
• a secretory unit (made of secretory cells), with underling supportive connective tissue called the secretory portion
Multicellular
Ex. Sweat glands, sebaceous glands (oily secretions), salivary glands, mammary glands, pancreatic glands.
Multicellular Exocrine Glands
Further sub-classified by:
-Structure of the ducts
-Shape of the secretory portion
-Mode of secretion
-Type of secretion
Subclassification of Multicellular Exocrine Glands
Mode of Secretion
Exocytosis of secretory vesicles; most common mode. (ex. Salivary glands, pancreas)
Merocrine
Done on “merit” - most common.
Subclassification of Multicellular Exocrine Glands
Mode of Secretion
Products collect apically and pinched off with part of the cell’s membrane. Blebs.
(Ex. Sweat glands of skin; lactating Mammary glands)
Apocrine (apo in Greek means “Away, off”)
Subclassification of Multicellular Exocrine Glands
Mode of Secretion
Programmed cell death; entire cell ruptures releasing secretory products and cell debris into lumen of gland. (Ex. Sebaceous glands)
Holocrine (cell becomes hollow as it explodes its intrels into its extrels)
Subclassification of Multicellular Exocrine Glands
Type of Secretion
• Viscous/slimy fluid secretion with extensive glycosylation
• Nuclei within cells are flattened & compressed to the base/periphery of cell
• PAS positive stain due to anionic oligosaccharides
• Mucinogen granules
- Store mucus
- Water soluble oligosaccharide is poorly preserved
- Pale staining (appear empty) on H&E staining
• E.g., minor salivary lingual glands, palatine glands
Mucous Glands
Subclassification of Multicellular Exocrine Glands
Type of Secretion
• Watery secretion with abundant protein content • Cells have typically rounded or oval shaped nuclei
• Apical cytoplasm filled with zymogen granules that stain eosinophilic
• Perinuclear cytoplasm is basophilic due to extensive rER
• Egs. • Exocrine pancreas • Parotid salivary glands
Serous Glands
Subclassification of Multicellular Exocrine Glands
Type of Secretion
• Contains both mucus and serous secretory components
• Serous demilunes
• Serous component of secretory unit hanging on mucus component in a half-moon shape
• Abundant striated ducts
• Egs • Submandibular salivary glands • Sublingual salivary glands
Mixed Glands
