An improved darkfield-illuminator for direct surface imaging of chromosomes.

An improved darkfield-illumination system for comfortable and convenient use of oblique incidence epi-illumination is described. The illuminator employs a new means for altering the position of the aperture diaphragm allowing a subtle adjustment of both the direction and the angle of the incident light bundle. The efficacy of this device for surface imaging is demonstrated in human chromosomes. The device permits an improved visualization of subtle Giemsa bands and the detection of sub-bands, which have not yet been described in the International System for Human Cytogenetic Nomenclature-High Resolution Banding.