Histology Lecture 3 - Epithelial Surface Specializations Flashcards
Microvilli are found on what surface of the cell?
Apical
What structure anchors microvilli?
Terminal web
Where are microvilli found in the body?
Small intestine and proximal convoluted tubule of the kidney
What are stereocilia? What are their features? Where are they found?
Microvilli. They are non-motile. Found in the male reproductive system and they are the sensory hair cells in the inner ear.
Are microvilli visible in the light microscope?
Not individually.
Are cilia and flagella visible in LM?
Yes
Where are cilia and flagella found?
Epithelial lining of the trachea and bronchi and epithelial lining of the uterine tubes.
What staining technique allows for best visualization of glycocalyx?
PAS (periodic acid schiff)
What is another name for zona occludens? Where on the cell are they found? What technique are they best visualized with?
AKA tight junctions. Found on lateral surface b/t cells. Freeze fracture is good to see these.
Where are zona adherens found?
On lateral cell surface BENEATH the zona occludens (tight junctions)
Where are desmosomes found?
Lateral cell surface.
What is the purpose of gap junctions?
Couple cells electronically.
What makes up gap junctions? How large is the gap b/t cells?
Made up of connexons, 2 nm gap.
What technique allows for visualization of gap junctions?
Freeze fracture and negative staining.
Describe the structure of the basement memberane.
Basal lamina is directly beneath epithelial cell and consists of the lamina lucida and lamina densa. Basal lamina is made of Type IV collagen, laminin, perclean, nidogen, and entactin links. Below the basal lamina is the reticular lamina, made of several types of collagen fibers.
What are basal infoldings diagnostic of?
They indicate that the cell is involved in ion transport or water transport.
What are typically associated with basal infoldings? What do these look like in the LM?
They are associated with mitochondria, which stain dark and look like big nuclei.
Where are cells with basal infoldings found?
Proximal and distal convoluted tubules and the STRIATED DUCTS of salivary glands.
What are the components of microvilli and terminal web?
Actin (microfilament) core. Terminal web is made of actin and myosin (thick filament)
What is stereocilia?
It is a modified microvilli
What is the structure of cilia and flagella? What is the motor protein?
Core of microtubules with motors (dynein). 9+2 arrangement in axoneme, 9+3 arrangement is found in basal bodies and centrioles.
Do the zonula junctions wrap around the cell?
Yes
Name two integral membrane proteins of the zonula occludins.
Claudins and occludins
Name the integral membrane protein and the peripheral membrane proteins for zonula adherens.
E-cadherins is the integral membrane protein. Catenins, alpha-actinin, and vinculin are the peripheral proteins.
What cytoskeletal protein is associated with zonula adherens?
Actin
What integral membrane proteins are associated with macula adherens?
Cadherins (subclasses are desmocollins and desmogleins)
Name the cytoskeletal protein associated with macula adherens.
Keratin
What protein is degraded in Pemphigus and Impetigo?
Desmoglein
What protein makes up gap junctions?
Connexins
What molecules make up the basal lamina?
TYPE IV COLLAGEN, perclean (a heparan sulfate proteoglycan), laminin, nidogen
What proteins make up the reticular lamina?
Reticular fibers (Type III collagen), and Type I collagen
What integral membrane proteins are associated with hemidesmosomes?
Integrins, Type XVII collagen
What cytoskeletal protein is associated with hemidesmosomes?
Keratin
What are tonofilaments?
Cytokeratins
What links basal lamina Type IV collagen and laminin together?
Nidogen and entactin
What are the transmembrane proteins in hemidesmosomes?
Collagen XVII and integrin.
