When are cells condensed and when are they decondensed?

Cells condenses at early pro phase and de-condenses at  late anaphase and telophase

Explanation:

When the protein mass and the nuclei acid mass is equal then it gives rise to a DNA- protein complex which is termed as Chromatin. The characters formation which is  the formation of chromosomes is taken care by the help of the chromatin. In the early stage of cell division that is in the propahse, the cell growth occurs that results in the formation of a thread like structure. The process of condensation takes place at this stage and slows down the process.

In early prophase of metazoan mitosis, the homogeneously distributed chromatin of inter phase begins to form visible thread-like structures. The decondensation process occurs at the satge called anaphase and telophase and it results in the re construction of the inter phase structure.

your answer is "the 1950's"