Which stain is referred to as a supravital stain?

• A. Camco Quik
• B. New methylene blue
• C. Eosin
• D. Sudan III or IV

Answer: (B)

Supravital staining is done on living, unfixed cells to reveal structures that would disappear after fixation. The classic example is staining fresh blood with New methylene blue, which highlights the residual RNA in reticulocytes and produces a blue, web-like network. This allows you to visualize immature red cells on a still-living sample, which is the hallmark of supravital staining.

The other options are typical stains used after fixation or for different purposes. Eosin is part of routine fixed cytology or histology stains and requires prior fixation. Sudan III or IV are lipid stains used on processed tissues to demonstrate fats, also requiring fixation and preparation steps. Camco Quik is a rapid stain used on prepared slides, typically after fixation. Because supravital staining involves unfixed, living cells to reveal features like the reticular RNA network, New methylene blue is the best match.