Mhc is an extended cluster of genes with extraordinary polymorphism , which consists of three classes of genes ( class i , class ii and classiii ) . they are different from each other in their structure , expression , mode of evolution and so on . class ii genes are further divided into two subclasses and the mhc genes spread over nearly all vertebrates extensively Mhc基因是一個(gè)高度多態(tài)的基因群,主要包括三大類(lèi)基因?類(lèi)( class ) 、類(lèi)( class )和類(lèi)( class )基因,它們無(wú)論在結(jié)構(gòu)組成、表達(dá)組織的類(lèi)型、刺激特定t細(xì)胞的類(lèi)群及長(zhǎng)期進(jìn)化等方面都有所不同;類(lèi)基因還可進(jìn)一步分為a 、 b兩個(gè)亞類(lèi):各類(lèi)基因廣泛分布于各種脊椎動(dòng)物體內(nèi)。