Abstract
We have attempted to verify that acquired characteristics can be transmitted through the male germ line by using as a model system the vertical transmission of specific immunological tolerance to major histocompatibility antigens. Tolerant males were a tetraparental mouse and separated parabionts, in each case showing stable lymphoid chimerism. Tolerance in the progeny was assessed by two in vivo assays, rejection of cardiac allografts and clearance of 131I-labeled tumor cells. We were unable to find evidence for heritability of the tolerant state in tetraparental or parabiont males, with either assay system.