Epithelial Cell Specializations Flashcards
Explain the concept of epithelial cell polarity
-Position of organelles
-apical surface characteristics
-cell to cell junctions
-cell basement membrane junctions
What specializations occur on the apical surface? (5)
- Microvilli
2.Cilia (motile) - Primary Cilia (non motile)
- Sterocilia
5.Glycocalyx
What are the specializations on the lateral surface? (4)
Zonula occludens
Zonula adherens
Macula adherens (Desmosomes)
Macula communicans (Gap junctions)
Although not usually visible on light microscopy, what specialization can be seen as a brush border? what surface is this a specialization?
Microvilli, apical
What filament supports microvilli?
actin which connects to the terminal web
Define glycocalyx
gelatinous glycoprotein-polysaccharide covering the cell membrane of some epithelia
Which stain would give you clear identification of the glycocalyx? and why?
PAS, because it targets the carbohydrates in the glycoproteins
What filament supports Cilia?
microtubules which are connect to basal bodies
What motor protein is supportive of microvilli?
Myosin
What motor protein is supportive of motile cilia?
Dynein
What is the main difference between motile cilia and non motile primary cilia?
The configuration of the microtubules, primary cilia lack the doublet as well as the dynein proteins
What filament supports stereocilia?
Actin
What physical characteristics differentiate sterocilia from motile and non motile cilia?
the length, the actin core, and the connections to adjacent stereocilia
Define zonula occludens
-first junction on the lateral surface
- provides selectively permeable barrier
What are the adhesive proteins and cytoskeleton protein of zonula occludens?
Occluden
Claudin
Actin
Define zonula adherens
-beneath zonula occludens
-mainly responsible for adhesion between cells
What protein forms the intercellular junction of zonula adherins? what is the cytoskeleton protein?
E-cadherin
Actin
What adhesive components and filament supports desmosomes (macula adherens)?
Desmoglein
Desmocollin
Intermediate filaments
What lateral surface specialization is integral to cell-cell bond strength?
Desmosomes (macula adherens)
What proteins comprise Gap Junctions (macula communicans)?
Connexins and connexons
What are the roles of the basement membrane (basal lamina)?
-Physical support
-Guide for cell adhesion and migration
- Cell signaling
What are the components of the basement membrane?
-Collagen (type IV)
-Glycoproteins
-Proteoglycans
What stain could you use to highlight the collagen in the basement membrane?
Silver
What is the purpose of basal infold and outfolds?
- Increase surface area for molecular transport
-Increase surface area for attachment
