Histology Flashcards
In order to visualize microscopic structure of tissue, it is typically cut into ______ um thick cross sections.
4 um
What are the issues with this approach?
- 3D structures are reduced to 2D
- Tissue becomes almost entirely transparent
What staining techniques can be used to overcome this?
- Hemotoxylin
- Eosin
- Nuclear fast red
- Alcian blue
What is hemotoxylin?
It is a basic, positive stain that binds to acidic cellular components like DNA. This stains the nucleus a blue to purple color.
What is Eosin?
It is a acidic, negative stain that binds to basic cellular components like proteins containing arginine and lysine. This stains the cytoplasm a pink to orange color.
What is Nuclear fast red?
It is a basic, positive stain that binds to DNA. This stains the nucleus a red color.
What is Alcian blue?
It is a basic, positive stain that binds to acidic polysaccharides like mucus. This stains mucus producing cells, like goblet cells in the small intestine, blue.
What are the three basic, morphological types of epithelial cells?
- Cuboidal cells
- Columnar cells (good for absorption/secretion)
- Squamous cells (good for diffusion)
What are the different epithelium?
- Simple epithelium (good for absorption/filtration).
- Stratified epithelium (good for protection)
- Keratinized epithelium (resistant to abrasion or chemical damage)
What are the 4 distinct layers of the gastrointestinal tract?
Lumen (inside space)
1. mucosa
2. sub-mucosa
3. muscularis mucosa
4. serosa
What are the different types of papillae?
- Filiform (numerous)
- Foliate (lateral)
- Fungiform (visible)
- Circumvallate (least abundant)
What is the mucosa comprised of?
epithelium, lamina propria, and muscular mucosae
What is the sub-mucosa comprised of?
immune cell, blood vessels, lymph vessels, and autonomic nerve fibers
What is the muscularis externa comprised of?
inner circular layer and outer longitudinal layer
What does the serosa do?
It prevents the various organs from adhering to one another
What are the different segments of the stomach?
cardia, corpus, and pyloric regions
What type of cells comprises the lining of the stomach? What do they do?
Fovealar cells which secrete an alkaline mucus which protects against the corrosive gastric acids
What are invaginations in the epithelium of the stomach called? Why do they exist?
gastric pits which serve as openings for the gastric glands
What cells comprise gastric glands? What do they secrete?
parietal cells - gastric acid
chief cells - gastric lipase and pepsinogen
What are the base of villi called?
crypts of Lieberkuhn
What is the epithelial lining of the small intestine comprised of?
- enterocytes
- enteroendocrine
- goblet cells
- paneth cells
What are Peyer’s patches?
organized lymphoid tissue of densely packed immune cells in the small intestine
