Structure and function of major histocompatibility complex.

The major histocompatibility complex (MHC) contains genes that control the structure of many important cell surface antigens and influence a variety of important biological functions. The structures of the MHC in the human, rat and mouse show a remarkable similarity both in terms of the location of their genes and the chemical structures of the gene products. Thus, the region of the chromosome containing the MHC has been highly conserved during evolution, and this finding suggests that its genes are important for survival. Another set of genes, which influences growth and development, is linked to the MHC in the mouse (T/t complex) and in the rat (Grc): this entire chromosomal region may function as a "supergene" with broad effects on tissue organization and compatibility.