Basic cytogenetics laboratory procedures

Abstract

The study of chromosomes using traditional cytogenetic techniques requires cells that are actively dividing. Chromosomes are individually distinguishable under the light microscope only during cell division and are best examined during metaphase. Metaphase chromosomes can be obtained from specimens that contain spontaneously dividing cells or ones that are cultured and chemically induced to divide in vitro. Specimens that contain spontaneously proliferating cells include bone marrow, lymph nodes, solid tumors tissue biopsies, amniotic fl uids, and chorionic villi. If there are not enough naturally dividing cells for a chromosome analysis, these specimen types may also be cultured in the laboratory without the aid of mitotic stimulants. Peripheral blood lymphocytes usually require the addition of a mitotic stimulant. The choice of specimen for chromosome analysis depends on clinical indications and whether the diagnosis is prenatal or postnatal.