1. Satellite chromosomes or SAT-chromosomes are chromosomes that contain secondary constructs that serve as identification. They are observed in acrocentric chromosomes. In addition to the centromere, one or more secondary constrictions can be observed in some chromosomes at metaphase. In humans they are usually associated with the short arm of an acrocentric chromosome, such as in the chromosomes 13, 14, 15, 21, & 22. The Y chromosome can also contain satellites, although these are thought to be translocations from autosomes. The secondary constriction always keeps its position, so it can be used as markers to identify specific chromosomes. The name derives from the small chromosomal segment behind the secondary constriction, called a satellite, named by Sergei Navashin, in 1912. Later, Heitz (1931) qualified the secondary constriction as the SAT state (Sine Acido Thymonucleinico, which means "without thymonucleic acid"), because it didn't stain with the Feulgen reaction. With time, the... from wikipedia.org