What characteristic is notable about Papanicolau stains?

Papanicolau stains, commonly known as Pap stains, are designed specifically for use with wet-fixed specimens. This characteristic is crucial because the process of preparing specimens for Pap testing involves fixing the cells on a slide to preserve their morphology and prevent degradation. Wet fixation allows the cellular details to be adequately maintained, which is essential for accurate visualization and interpretation during microscopic examination.

The other options do not capture the defining feature of Papanicolau stains. For instance, while quick results are important in clinical settings, Papanicolau stains do not inherently provide rapid results compared to some other staining techniques. Additionally, the staining of red blood cells is not a primary focus of Pap stains, as they are primarily used to assess epithelial cells. Lastly, while cost is a consideration in clinical laboratory practices, the statement about being the least expensive option does not apply universally, as the costs can vary based on many factors, including laboratory practices and geographic location.