Tissue

Epithelial Connective Muscle Nervous

Light MICROSCOPE: up to 0.2μm Electron MICROSCOPE: up to 0.2nm -transmission electron MICROSCOPE (TEM) -scanning electron MICROSCOPES (SEM)

Specimen: as fresh as possible Fixation: Preserves tissue structure (e.g., formaldehyde) Postfixation: dehydration(ethanol) and then clear specimen (xylene) Embedding: cover tissue with paraffin wax or resin Sectioning: Cutting thin slices (5-10 micrometers) for microscopy Staining: Enhances contrast in tissue sections (e.g., Hematoxylin and Eosin (H&E) stain)

Hematoxylin Eosin Basophilic Acidophilic Neutrophilic

Basic dye, blue dye that stains acidic cell parts (like the Nucleus)

Acidic dye, pink dye that stains basic cell parts (like the cytoplasm)

stained with basic (blue) with hematoxylin (nuclear chromatin)

stained with acidic (pink) with eosin (nuclear chromatin)

don't stain well with either dye.

Nuclei: Black or blue-black Muscles: Red Collagen & Mucus: Green or blue Cytoplasm: Pink

those with a react for silver, dark-brown color

Wright or Giemsa staining

Microscope using electrons for high Enlargement See small cell shapes Uses electron beam, not light. Sample prep: plastic, very thin sections (50-70nm), heavy metal stains resolution (0.1-0.5nm) shows ultrastructure

Show 3D surface Shape of cells and tissues Resolution: 5nm

Longitudinal section Cross section Oblique section

Cut long

Cut at middle