Marchi's Method involves a series of steps to selectively stain degenerated myelin. Initially, the tissue is fixed, typically using a solution containing osmium tetroxide. Osmium tetroxide binds to unsaturated fats, which are abundant in degenerated myelin. The tissue is then sectioned and treated with reagents that enhance the contrast between healthy and degenerated myelin. The degenerated myelin appears black or dark brown, whereas healthy myelin remains unstained or lightly stained.
