Cell Arrest and Harvest

The chromosomes reach their maximum level of condensation during metaphase. One way to obtain a sufficient number of high quality metaphases is to have many actively dividing cells. We can obtain the cells from biopsy or from amniotic fluid.

Time

Culture harvest time is critical. Cells with a high confluency rate will have a lower division rate with fewer mitoses available for analysis. This may affect the possibility to exclude mosaicism or interpreting abnormal results by analyzing additional mitoses. If the culture is harvested too early there might be too few mitotic cells. The cells are usually harvested at day 8-14.

Colcemid

Colcemid or colchicine is added to the culture to arrest the cells in metaphase. Colcemid works by preventing the formation of the microtubules that attach to the centromere in order to separate the two sister chromatids during the mitotic anaphase.