Which biological stain is used in histology and cytology to colour all cell nuclei red?

Safranin

The correct answer is Option (2) – Safranin

The biological stain used in histology and cytology to color all cell nuclei red is Safranin.

Explanation:

• Safranin is a commonly used histological stain that belongs to the family of basic dyes.
• It is used to stain cell nuclei, cartilage, and some other tissues in different shades of red.
• In histology and cytology, stains like Safranin are crucial for enhancing the visibility of cellular structures and tissues under a microscope.
• Safranin is often used in conjunction with other stains, such as Fast Green or Light Green, to achieve a contrast between different cellular components.

In the staining process, Safranin binds to nucleic acids, such as DNA, in cell nuclei, allowing researchers and pathologists to observe and analyze cellular structures and arrangements.