Light Microscopy Flashcards
Tissue
A collection of cells specialised to perform a particular function
(an aggregation of tissues constitute organs)
Histology
used for final proof before diagnosis
The study of structure of tissues by means of special staining techniques combined with light and electron microscopy
Units of measurement
MUN
Metre - m - 10^1m Millimetre - mm - 10^-3m Micrometre - um - 10^-6m Nanometre - nm - 10^-9m Angstrom Unit - Å - 10^-10m
Human cells
usually 10-20um in diameter
Oocyte - 100um (0.1mm)
RBC - 7.2um
Biopsy
The removal of a small piece of tissue from an organ or part of the body for microscopic examination
Smear
Collect cells by spontaneous/mechanical exfoliation - smear on slide
e.g. Cervix or Buccal cavity
Curettage
sharp edged spoon
Removal of tissue by scooping/scraping
e.g. Endometrial lining of uterus
Needle
Put needle into tissue to gather cells
e.g. Brain, beast, liver, kidney, muscle
Direct incision
Cut directly into tissue of interest and remove tissue
e.g. Skin, mouth, larynx
Endoscopic
with camera
Removal of tissue via instruments through an endoscope
e.g. Lung, intestine, bladder
Transvascular
e.g. Heart, liver
Tissue processing
Fresh biopsy is wet and blood
Fixation by glutaraldehyde, formaldehyde
Fixed biopsy (macromolecules are cross-linked, cellular structure preserves, no autolysis (by lysosomes) and no putrefaction (bacteria has been killed)
Fixation
can cause shrinkage artefacts due to repeated dehydration and rehydration
Dehydration by ethanol Cleaning of ethanol by xylene/toluene Biopsy is impregnated and embedded in wax Sectioned - 15mm across Rehydrated Stained Dehydrated again Then mounted - READY FOR MICROSCOPIC EXAMINATION
Haematoxilin and Eosin
Haematoxylin - stains ACIDIC components of cells PURPLE/BLUE e.g. Nucleolus and chromatin
Eosin - stains BASIC components of cell PINK
e.g. most cytoplasmic proteins and extracellular fibres
The Periodic Acid-Schiff
PAS
stains carbohydrates and glycoproteins magenta
