Used in cytogenetics

Cytogenetics

Cytogenetics is a branch of genetics that is concerned with the study of the structure and function of the cell, especially the chromosomes. It includes routine analysis of G-Banded chromosomes, other cytogenetic banding techniques, as well as molecular cytogenetics such as fluorescent in situ...

, colcemid, also known as demecolcine, is related to colchicine

Colchicine

Colchicine is a medication used for gout. It is a toxic natural product and secondary metabolite, originally extracted from plants of the genus Colchicum...

 but it is less toxic. It depolymerises

Depolymerization

Depolymerization is the process of converting a polymer into a monomer or a mixture of monomers.Thioglycolysis, thiolysis and phloroglucinolysis are reactions used to study condensed tannins by means of their depolymerisation. Thioglycolysis is also used to study lignin....

 microtubules and limits microtubule formation (inactivates spindle fibre formation), thus arresting cell

Cell (biology)

The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

s in metaphase

Metaphase

Metaphase, from the ancient Greek μετά and φάσις , is a stage of mitosis in the eukaryotic cell cycle in which condensed & highly coiled chromosomes, carrying genetic information, align in the middle of the cell before being separated into each of the two daughter cells...

 and allowing cell harvest and karyotyping to be performed.

Mechanism of Action

Colcemid is a microtubule-depolymerizing drug like vinblastine

Vinblastine

Vinblastine is an antimicrotubule drug used to treat certain kinds of cancer, including Hodgkin's lymphoma, non-small cell lung cancer, breast cancer, head and neck cancer, and testicular cancer. It is also used to treat Langerhan cell histiocytosis....

. It acts by two distinct mechanisms. At very low concentration it binds to microtubule plus end to suppress microtubule dynamics. Recent study has found at higher concentration colcemid can promote microtubule detachment from microtubule organizing center. Detached microtubules with unprotected minus end depolymerizes with time. Cytotoxicity of the cells seems to correlate better with microtubule

Microtubule

Microtubules are a component of the cytoskeleton. These rope-like polymers of tubulin can grow as long as 25 micrometers and are highly dynamic. The outer diameter of microtubule is about 25 nm. Microtubules are important for maintaining cell structure, providing platforms for intracellular...

detachment. Lower concentration affects microtubule dynamics and cell migration.