Histology

Question 1

Tissue processing for histology

Answer 1

1. Fixation: freezing (-80) dry ice/liquid nitrogen, chemical fixation, aldehyde based. Use: to preserve the tissue
2. Embedding: frozen samples, paraffin wax. Use: provides support for the tissue when sectioning.
3. Sectioning: the thinner the slice the higher the resolution, use microtome to cut thin sections. Use: 2D representation of 3D objects
4. Staining: colours tissue

Question 2

Staining

Answer 2

• haematoxylin: basic, stains acidic structures purple eg. Nucleus
• eosin: acidic, stains basic structures pink eg cytoplasm
  PAS- staining complex carbs and glycogen, magenta
  Stains mucus, BM

Question 3

Epithelial tissue

Answer 3

• covering epithelia: covers/lines all body surfaces, cavities and tubes
• grandiose epithelia: secretory epithelium arranged into glands, invaginations of epithelium, also glandular organs
• exocrine glands: retain continuity with surface- secrete via duct
  -endocrine glands: lose contact with surface- secrete directly into bloodstream

Question 4

Epithelial tissue: number of layers

Answer 4

• simple: single layer, good for absorption/secretion, fragile
• stratified: 2 or more layers of cells, good for protection
• pseudostratified: one layer with mixture of cell shapes

Question 5

Epithelial tissue: shapes of cells

Answer 5

• squamous: flat shaped
• cuboidal: cube shaped
• columnar: talk cylindrical shaped
• transitional: readily change shape, accommodates stretching ( expansion/ movement of body)