Axolotl MHC architecture and polymorphism

The MHC of the urodele amphibian Ambystoma mexicanum consists of multiple p olymorphic class I loci linked, so far as yet known, to a single class II B locus. This architecture is very different from that of the anuran amphibi an Xenopus. The number of class I loci in the axolotl can vary from 6 to 21 according to the haplotypes as shown by cDNA analysis and Southern blot st udies in families. These loci can be classified into seven sequence groups with features ranging from the class la to the class Ib type. All individua ls express genes from at least three of the seven groups, and all individua ls possess the class la-like type.