Introduction to Histology Flashcards
Define pathology, histo-pathology, and histology
Pathology = study of disease processes Histo-pathology = study of disease processes at the cellular level Histology = study of fine tissue structures by rendering 3D structures into 2D
What are tissues?
Collections of cells of similar structure that function together as a unit
Usually in an extracellular matrix
What are the 6 key steps in histological specimen preparation?
- Fixation
- Dehydration
- Infiltration
- Embedding
- Sectioning
- Staining
What is fixation?
Fixing tissue cells to stop degradation and metabolism of cells / shrinkage
Commonly use formalin
What is the purpose of dehydration?
This gets tissues to allow / accept infiltration by an embedding medium
What is infilitration?
Tissues are filled with a liquid form of embedding medium eg epoxy resin
What is embedding?
Allowing infiltrate to harden
What is sectioning?
Preparing very thing slices of embedded tissue via glass / diamond knives
What is staining?
Sections are stained to visualise the thin slides of tissues - appearance will differ with different stains
Why is light microscopy more common than transmission electron microscope (TEM)?
Easier to use
Lower resolution than TEM but usally able to make out enough detail
Phase contrast light miscroscopy allows you to see living cells
What is the main difference in prepping sections for light microscopy as opposed to TEM?
Paraffin embedding is used more so than plastic (epoxy resin)
What are the most common stains used and their prime attributes?
Hematoxylin = Basic dye = net positive charge, attracted to negative charged groups eg DNA, RNA, and extracellular carbohydrates
Eosin = Acidic dye = net negative charge, attracted to positive charged groups eg most proteins
