Cell culture research. Researcher pipetting basal medium into a petri dish. Basal medium is an agar-based substance used to grow cells in the lab. It contains all the nutrients, growth factors and hormones needed for specific tissue cells to grow when incubated at the correct temperature. The cells grown in these dishes will be used in cytogenetic research, the study of how chromosomes function and the effects of chromosomal abnormalities. Chromosomes are composed of the genetic material, DNA (deoxyribonucleic acid) and proteins. Photographed at Leiden University Medical Centre, Leiden, The Netherlands.