Which of the following is NOT an effect of fixation?

Fixation is a crucial step in cytogenetics that involves the preservation of cellular structure and the enhancement of the properties necessary for microscopic evaluation. The process of fixation serves to stabilize the cell structure, which allows for the cellular components to be adequately preserved for further analysis.

When fixation is performed, it ensures that the cells maintain their morphology, allowing for accurate microscopy and subsequent evaluation of chromosomal arrangements. Additionally, fixation enhances staining properties, making it easier to visualize specific cell components or chromosomes through the use of various dyes or stains.

Colcemid, on the other hand, is a drug that is used to halt cell division (mitosis) by disrupting the spindle formation during metaphase. It is not a fixation agent and does not contribute to the preservation or enhancement of cell structures or morphology. Instead, Colcemid serves a different purpose in cytogenetic studies, such as synchronizing cells prior to fixation, but it is not a direct effect of the fixation process itself. Thus, the choice that states "A short exposure to Colcemid" does not pertain to the effects of fixation and is the correct answer.