Gut Histology Flashcards
What does most epithelial tissue line?
cavitities and surfaces
apical side touches the lumen
Basement membrane
normally separates epithelial tissue from connective tissue lamina propria
Is basement membrane an actual membrane?
no
it is made of extracellular material
What does basement membrane bind to?
hemidesosomes
What is main collagen type of connective tissue?
type I collagen
Do epithelial cells contain an abundance of collagen?
no
Does epithelial tissue secrete components of basal lamina?
yes
What are microvilli made of?
actin filaments
What type of cells have microvilli?
intestine
can form a “brush border”
What type of cells have cilia?
respiratory tract cells
important for mucus movement
What is true in general of cilia?
they help with movement
Simple epithelia
single layer of cells, all of which rest on basement membrane
can have different shapes
Where is simple epithelia normally found?
where exchanges occur
such as blood capillaries and air spaces of lungs
Simple squamous epithelial cells
mesothelium and endothelium
blood cavities
Simple squamous cell shape
wider than they are tall
Simple cuboidal epithelial cells
found in many of the ducts
ex: parotid gland
Simple columnar cells
normally found in the digestive tract
Where is the brush border found?
normally in the gut
What is brush border made of?
actin
Pseudostratified epithelium
NOT stratified
all cells do touch the basement membrane
the nuclei are just at different heights
Connective vs. epithelial tissue
connective tissue is much less dense than epithelial
Stratified epithelia
multiple layers of epithelial cells but only the basal layer of cells rests on basement membrane
Stratified squamous
top layer consists of flattened cells
two types of stratified squamous
1) Keratinized
2) Non-keratinized
where are non-keratinized stratified squamous cells found?
moist surfaces that are still exposed to elements
like the mouth
transitional epithelial cells are found?
urinary tract / bladder
How can you identify transitional epithelial cells?
there are no neat rows to the layers
however, there are still multiple layers
What can transitional epithelial cells often be confused with?
stratified cubodial
however, this doesn’t have neat rows
Mucosae
generally moist regions that are coated with mucus
layers of GI tube from inner to outer
mucosa (includes epithelial)
submucosa
muscularis externa / propria
adventitia OR serosa
What are the 3 layers of the mucosa (innermost layer)?
epithelium
lamina propria
muscularis mucosae
Where is connective tissue?
in the lamina propria
in the submucosa (primarily)
Esophageous epithelial cells
stratified squamous
allows us to transport food
How do you stain connective tissue?
you actually stain extracellular products not the tissues themselves
What does muscularis mucosae stain?
pink / red
Serosa vs. adventitia location
adventitia is outermost layer of esophagus
serosa is outermost layer of most of the digestive tract (visceral peritoneum)
Adventitia appearance
blends into the surrounding tissue
no defined borders
Epithelium of the colon
Simple column cells
specialize in water absorption
have crypts
Crypts
straight tubular elements in the epithelial layer of colon tissue
Submucosa of the colon
expansive
contains many large blood vessels to transport water out of GI
Serosa of colon
simple squamous epithelial covering
often CANNOT see on slides
Pseudomembranes
composed of inflammatory cells and debris in locations where the mucosa has been injured and denuded
