chromatin is composed of
chromatin. the substance of the chromosomes, composed of nucleic acids and basic proteins (histones), the material in the nucleus that stains with basic dyes. sex chromatin. Barr body; the persistent mass of the material of the inactivated X chromosome in cells of normal females.See also drumstick.hromatin. the substance of the chromosomes, composed of DNA and basic proteins (histones), the material in the nucleus that stains with basic dyes.