Histology Flashcards
Which epithelia is most likely to be composed of simple cuboidal cells?
Ducts and tubules
- collecting tubules
- salivary and pancreatic secretory ducts
Which epithelia is most likely to be composed of simple cuboidal cells?
Absorptive surfaces = GI tract and stomach
Which filaments maintain the structure of mcirovilli?
Actin filaments
What are goblet cells?
They are modified columnar cells which secrete mucous
How do goblet cells stain with H and E stain?
Poorly due to mucous being ‘washed out’
Which epithelia is most likely to be composed of pseudostratified epithelia?
The respiratory tract
What filaments give cilia their shape and what is the arrangement of these filaments?
Cilia have a core or X20microtubules
Arranged of X9 pairs circling a central pair
What are the X4 main layers of the respiratory system?
State what each of these layers contains.
1) mucosa
= epithelium
= lamina propria
2) Submucosa
3) cartilage/smooth muscle
4) Adventitia
What type of epithelia are found in the respiratory tract?
Pseudostratified columnar epithelia with cilia and goblet cells
What type of epithelia are found in the oesophagus?
Stratified squamous epithelia (non-keratinising)
What type of epithelia does skin have?
Stratified squamous epithelia (keratinising)
What does keratinising mean?
How will these appear under microscopy?
It means the top layers are dead keratinised cells with no nuclei due to keratins being linked with disulphide bonds
Flat and thin
What is transitional epithelium?
Where is it found?
Epithelium that can be distended
Only found in the urinary tract
What colour is the connective tissue when stained?
Usually pale as it does not stain well and mainly consists of extra-cellular matrix
It’s few cells are highly scattered (fibroblasts)
In connective tissue, what is ground substance?
A watery gel of proteiglycans synthesised from glycosaminoglycans (GAG’s)
What is extracellular matrix?
Proteins embedded in the watery gel ground substance (GAG’s)
What are the main proteins found in the ECM?
Elastin
Collagen
Fibronectin
Laminin
What do fibroblasts do?
Synthesise ECM (ground substance) and collagen
Other than fibroblasts, what other cells are permanently found in connective tissue?
Adipose cells
What are the X3 types of connective tissue?
Give examples of each.
1) basal lamina
2) loose (areolar) = mesentery and hypodermis
3) dense
Dense connective tissue is further subdivided into?
Give examples of each.
1) regular
= tendon/ligament
2) irregular
= dermis of skin
Which appear thicker under microscopy, collagen or elastic fibres?
Collagen fibres
What would dense, regular connective tissue look like?
Parallel collagen fibre bundles with fibrocytes in between
What are tendons mainly made from?
Collagen fibres
Can skeletal muscle cells divide?
If not what overcomes this?
No
Satellite cells
What is the structure of muscle from sarcomeres to the whole muscle?
Sarcomeres
Multiple sarcomeres = myofibril
Multiple myofibrils = myofibre (muscle fibres)
Multiple muscle fibres are bound together into fascicles
Fascicles join to make the muscle
Which types of muscle does NOT have gap junctions?
Skeletal, the other X2 types do
What would you look for under microscopy to see skeletal muscle?
- striated cells
- multinucleate with nuclei at peripheries
What would you look for under microscopy to see cardiac muscle?
- uninucleate cells with centrally locates nuclei
- striated
- intercalated discs
What would you look for under microscopy to see smooth muscle?
- no striations
- uninucleate with centrally located nucleus
- spindle shaped cells (tapered ends)
What is the name of the connective tissue which capsules around cartilage?
Perichondrium
What cells are located in perichondrium and what do they do?
Fibroblasts which produce chondrocytes which themselves produce cartilage
What is growth called when it occurs from the outside in, as seen with chondrocytes synthesising cartilage?
A positional growth
Cartilage has X2 types of growth, what are these?
Apositional and interstitial growth
What type of growth does bone undergo?
Apositional only
Where about a do blood vessels run with regards to cartilage?
In the perichondrium
In haversack systems, what is the name of the central canal which is encircled with bone?
Haversian canal
What is the name of the concentric circles of bone which surround the Haversian canal?
How many of these surround each canal?
Lamellae
4-20
What do haversian systems carry?
Vessels and nerves
But NOT lymphatics
What is an alternative name for the Haversian canals?
Osteons
What structure connects Haversian canals transversely?
What is their function?
Volkman’s canals
Allow blood to pass between Haversian canals
What is the name of the remnants of osteons/Haversian canals which are currently ‘turning over, found between fully developed osteons?
Interstitial lamellae
What are the X2 patterns in which lamellae are laid down within bone?
1) Haversian systems
2) circumferential around the edge of bones
What are lacunae?
Small gaps between concentric circles of lamellae collagen which house osteocytes
What are osteocytes?
Osteoblasts (bone matrix secreting cells) which have synthesised matrix then embedded themselves in it
What are the small cavities which extend lacuna to lacuna?
Canaliculi
What bone cells degrade old bone to make room for new osteoblasts?
Osteoclasts
What are the X4 main layers of the GI tract?
What does each layer contain?
1) mucosa
- epithelium
- lamina propria
- muscularis mucosae
2) Submucosa
3) muscularis externa (propria)
4) Adventitia or serosa
How would you decide when the Submucosa layer of the GI tract starts under microscopy?
The layer becomes much white and fewer cells are apparent
How does the epithelium specialisations of the GI tract change as it progresses?
1) it begins as protective
2) then turns secretory
3) then absorptive
4) finally returns to protective
Which plexus of nerves is found in the Submucosa?
Meissner’s plexus
What does the muscularis mucosae delineate between?
The end of the mucosal layer (1st layer) and the submucosa (2nd layer)
What is another name for the muscularis externa?
Muscularis propria
How many layers does the muscularis externa have?
What are they?
1) inner circular layer of muscle
2) outer longitudinal layer of muscle
Where is Auerbach’s plexus of nerves situated?
Between the inner circular and outer longitudinal layer of the muscularis externa layer of the GI tract
How thick would the Adventitia / serosa layer appear under microscopy?
Thin, almost a small edge!
What cells line the Adventitia/serosa?
Simple, squamous mesothelium
What is the epithelium of the oesophagus?
Stratified, squamous epithelium (for protection)
NON-KERATINISING!
What does the epithelium change to at the gastro-oesophageal junction?
It changes to simple, columnar epithelium
Which part of the GI tract has an extra layer?
What is this layer?
The stomach
A inner oblique muscle layer within the muscularis externa (is the most inner layer)
Which stomach cells secrete pepsinogen?
Chief cells
Which stomach cells secrete HCl?
Parietal cells
Which cells of the gastric pit are most likely to line the top and sides of the pit?
Neck mucous cells
Which cells of the gastric pit are most likely to line the isthmus?
What do these look like under microscopy?
What do they secrete?
Partial cells
Like fried eggs, large and round
HCl and intrinsic factor
Which cells of the gastric pit are most likely to line the lower regions of the gastric glands?
What do these look like under microscopy?
Chief cells
Nasally located nuclei and dense with granules
Pepsinogen
What are alternate names for chief cells?
Peptic or zymogenic cells (as they contain zymogen granules)
What is an alternative name for parietal cells?
Oxyntic cells
How would identify a specimen between:
1) Caria mucosa or stomach
2) body mucosa of stomach
3) pyloric mucosa of stomach
1) Caria mucosa or stomach
= glands are sparse
2) body mucosa of stomach
= glands are densely packed
3) pyloric mucosa of stomach
= very deep pits
What is the epithelium of the small intestine?
Simple columnar (same as stomach) but with a brush boarder of microvilli (surface specialisation)
In the small intestine, what is the difference between plicae circularis and villi?
Plica = evaginations of the whole mucosa layer and some of the submucosa
Villi = evaginations of the mucosa layer only
What lies between villi in the small intestine?
The crypts or leiberkühn
What cells are found in the crypts of leiberkühn?
Where are these found within the crypts
What do these do?
What do they look like under microscopy?
Paneth cells
Found in the lower 1/3
They release digestive enzymes
They have a nasally located nuclei and stain bright pink!
What feature do small intestine epithelia have to prevent digestive enzymes destroying host tissues?
Glycocalyx
Does the small intestine have goblet cells?
Yes
Other than paneth cells, what other cells are found deep in the lower 1/3 of the crypts of leiberkühn?
What is their function?
What do they look like under microscopy?
Endocrine cells
They release multiple hormones
They stain very light in their cytoplasm
What glands are found distinctively in the duodenum?
What do they look like?
Brunners glands
They are found in the submucosa but pierce the muscularis mucosae and drain into the crypts
What other distinguishing feature does the duodenum have?
Leaf shapes villi
Does the jejunum have brunners glands?
No
What do jejunum villi look like?
Long, tall and thin (NOT leaf shaped!)
What is found in the ileum that is not found in the duodenum and jejunum?
Which layer is this found in?
Peyers patches
Then lamina propria
What do ileum villi look like?
Much shorter
What does the appendix look like under microscopy?
It has lots of tiny dots (lymphocytes)
What does the epithelial layer of the large intestine look like?
No villi
Lots of goblet cells for mucous secretion
What is different about the muscular layer in the large intestine?
Teniae colicand haustra
What does the epithelium change to at the ano-rectal junction?
Changes to stratified squamous epithelium
What will be seen in the muscle layer of the anal canal?
The internal and external sphincters
