The study of chromosomes using traditional cytogenetic techniques requires cells that are actively dividing.Overview of cell culture and harvest
Culture initiation -> Culture maintenance -> Cell harvest
o Sterility Living cells o Arrest division o
o Optimal temperature Sterility o Swell cells o
o Optimal pH Proper growth medium o Fix cells o
o Optimal humidity +- Mitotic stimulant o Prepare slide o
o Optimal time interval Microbial inhibitors o Stain/band o
 The most critical requirement is that living cells capable
of cell division be received by the laboratory.Specimens that contain spontaneously proliferating cells
include bone marrow, lymph nodes, solid tumors tissue biopsies, amniotic fl uids, and chorionic villi.Specimen Collection and Handling
 Sample Requirements
 Peripheral Blood Specimens
 Peripheral blood samples should be collected in sterile
syringes or vacuum tubes containing preservative-free
sodium heparin.Metaphase chromosomes can be obtained from specimens that contain spontaneously dividing cells or ones that
are cultured and chemically induced to divide in vitro .Specimen
containers must be sterile and must be labeled with the
patient's name and a second identifi er. The laboratory may
reject specimens that are improperly labeled or unlabeled.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.The choice of
specimen for chromosome analysis depends on clinical indications and whether the diagnosis is prenatal or postnatal.The manner in
which the sample is collected and subsequently handled will
greatly in fl uence whether or not the cells will grow and
divide, and the quality of the resulting metaphases.The individual details of culture initiation, maintenance,
and cell harvest vary somewhat for the different sample
types; however, the general steps and requirements are similar.Chromosomes
are individually distinguishable under the light microscope
only during cell division and are best examined during metaphase.Bone marrow
aspirates should be collected in sterile syringes or vacuumIt is not always practicable or possible to
obtain a new sample, and in such cases, the laboratory should
attempt to salvage the original specimen.Bone Marrow Aspirates
 The collection requirements for bone marrow samples are
essentially the same as for peripheral blood.Peripheral blood lymphocytes usually require the addition of a mitotic stimulant.Vacuum tubes should be discarded if outdated.Temperature extremes must be avoided if samples are transported or stored.These are summarized below .