[The major OLA histocompatibility complex of sheep. Recent results in the genetic study of 11 factors previously defined by microlymphocytotoxicity].

The genetic study of 11 lymphocyte factors previously described in sheep was continued. 9 factors are the products of alleles at two closely linked loci OLA-A and B. The last two factors are the products of two genes at two distinct loci OL-X and OL-Z. Recombinations between the two closely linked loci are very rare (0.6%); but they are frequent between these two loci and OL-X (26%). The OL-Z locus seems to be independent of the two linked loci OLA-A and B. The allele frequencies at the four loci are given.