Why can karyotyping only be carried out only when the cells about to divide?

In order to understand why karyotyping can only be done on cells that are about to divide, one must first understand what karyotyping is. Karyotyping is a technique used to visualize the chromosomes that are located within a single cell. This visualization allows scientists to examine the size, number, arrangement, and structure of the chromosomes present. This is important because karyotyping can then be used to look for specific genetic conditions, such as trisomy of a chromosome, or translocations of one part of a chromosome to another nonhomologus chromosome, both of which can lead to major physiological complications and consequences. The reason cells must be close to dividing for this technique to be used is because chromosomes are actually found as long thin structures in a non-dividing cell. These structures are to fine to be labeled and imaged. However when the cell is going through the replication process, these structures are wound into a tighter form that is large enough to be both labeled and visualized through microscopy. Typically, in a normal karyotyping test, scientists will analyze and compare the chromosome sets of at least 10 different cells to help confirm their findings. Hope this helps!