Sister chromatid exchange

Sister chromatid exchange is the exchange of genetic material between two identical sister chromatids.It was firstly discovered by using giemsa staining method on one chromatid belonging to the sister chromatid complex before anaphase in mitosis. The staining revealed that few segments were passed to the sister chromatid which was not dyed.The giemsa staining was able to stain due to the presence of 5-brom-deox-uridine anologous base which was introduced to the desired chromatid.
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An exchange (crossing-over) of genetic material between the two (identical) chromatids of a chromosome in mitosis (mitotic recombination). Normally, genetic recombination takes place between homologous chromosomes in meiosis I. Sister chromatid exchange may be a sign of chromosomal instability but has no genetic consequences as long as the exchange is the result of an equal crossover.