X-Ray

A term used to describe electromagnetic radiation using a wavelength that is shorter than visible light. X-rays are produced when high speed electrons strike heavy materials such as tungsten and can penetrate most sustances. They are used to verify the integrity of certain structures (such as bone) and therapeutically destroy tissue.

They are best known when referring to the photographic images used for diagnostic purposes using x-rays. They are created by projecting x-rays through the body onto a photograhic plate. Since some structures, such as bone, absorb more x-ray energy, an image is created of the internal body structure.

XX/XY Chromosomes

The chromosomes that determine male and female sex characteristics. In genetics XX is the designation for the normal sex chromosome complement in females. XY is the designation for the normal sex chromosome in males.