What is the correct sequence for Gram Twort stain?

Study for the CAMLPR Histology Practice Test. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

The sequence being tested is the four-step Gram stain that uses differences in cell wall structure to distinguish bacteria. Start by applying Crystal Violet to color all cells purple. Then add Iodine, which forms a Crystal Violet–Iodine complex that helps fix the dye in place. The decolorization step then uses ethanol (or acetone–alcohol) to wash away the dye from cells with a thinner peptidoglycan layer and an outer membrane (Gram-negative), while cells with a thick peptidoglycan layer (Gram-positive) retain the dye. Finally, apply a counterstain such as Safranin to color any decolorized cells; Gram-negative cells appear pink/red, and Gram-positive cells remain purple. Acid alcohol isn’t the standard decolorizer for this method and can over-decolorize, while methylene blue isn’t used in this four-step sequence. In short, the typical order is Crystal Violet, Iodine, Ethanol (or acetone–alcohol), Safranin.