Which feature identifies a mitotic figure under light microscopy?

• A. Large vacuolated cytoplasm
• B. Prominent nucleolus with diffuse chromatin
• C. Incomplete nuclear envelope
• D. Condensed chromosomes visible during mitosis

Answer: (D)

Mitotic figures are identified by condensed chromosomes visible during mitosis. When a cell enters mitosis, chromatin condenses into distinct, dark-staining chromosomes that can be seen as rod-like or thread-like structures under light microscopy, signaling active division. The other features describe non-mitotic or different mitotic stages: a large vacuolated cytoplasm indicates cytoplasmic changes; a prominent nucleolus with diffuse chromatin corresponds to interphase where chromatin is not condensed; and an incomplete nuclear envelope can occur in some mitotic stages, but without condensed chromosomes you don’t have a mitotic figure. So the presence of condensed chromosomes is the hallmark that identifies a mitotic figure.