Colcemid, also known as demecolcine, is a synthetic analog of colchicine. It is less toxic to cells than colchicine. Being a mitotic inbitor, colcemid binds to the tubulin protein and obstructs the spindle fibre formation. At very low concentration it binds to microtubule plus end and affects the microubule dynamics by causing depolymerisation. It effectively arrests cell in metaphase, allowing cell harvest and karyotyping to be performed. Colcemid is used to arrest different types of cells in metaphase like peripheral blood cells, amniotic fluid cells, fibroblasts, bone marrow cells and cells from chorion villus samples, etc. Exposure of cells to colcemid depends upon quantity of colcemid and the type of cell. A longer exposure will result in more metaphases but with shorter chromosomes. Longer chromosomes are generally preferred for cytogenetic studies. TCL074 is a sterile filtered solution of 10µg per ml of Colcemid is Hank's balanced salt solution.