The process of preparing tissues for histological analysis generally involves several key steps:
Fixation: Preserves the tissue structure by stabilizing proteins and other molecules. Common fixatives include formaldehyde and glutaraldehyde. Embedding: The tissue is encased in a solid medium, usually paraffin wax or a resin, to facilitate thin sectioning. Sectioning: Thin slices of the tissue are cut using a microtome or cryostat, typically ranging from 3 to 10 micrometers thick. Staining: The tissue sections are stained to enhance contrast and reveal specific structures. Common stains include H&E, PAS (Periodic Acid-Schiff), and Masson's Trichrome. Mounting: The stained sections are placed on glass slides and covered with a coverslip for microscopic examination.
