Chromosome transfer — individual whole chromosomes are most suitably isolated for transfer at which mitotic stage, when they are maximally condensed?

Introduction / Context:
Cytogenetic manipulations, including micromanipulation or microcell-mediated chromosome transfer, require intact, highly condensed chromosomes. The mitotic stage determines chromosome morphology, visibility, and ease of isolation.

Given Data / Assumptions:

• Goal: isolate whole, discrete chromosomes.
• Chromosome condensation varies across mitosis.
• Technical success improves when chromatids are compact and distinct.

Concept / Approach:

Metaphase is the phase where chromosomes are maximally condensed and aligned at the metaphase plate. This makes them easiest to visualize, separate, and transfer compared with less condensed stages such as prophase or decondensing stages like telophase.

Step-by-Step Solution:

Verification / Alternative check:

Standard karyotyping arrests cells in metaphase (e.g., with colchicine), precisely to visualize distinct chromosomes, underscoring suitability for isolation.

Why Other Options Are Wrong:

Prophase condensation is incomplete; anaphase chromosomes are segregating; telophase shows decondensation; interphase chromosomes are diffuse (chromatin state).

Common Pitfalls:

Confusing “visible” with “isolatable”; while chromosomes are visible in late prophase, they are not as discrete and manipulable as at metaphase.

Final Answer:

Metaphase