“…It is now realized, however, that the brain is not so privileged. Rejection of foreign solid tissue grafts occurs in the brain just as it does elsewhere (Scheinberg et al, 1967;Lance, 1967a, b;Dixit & Coppola, 1969), although rejection is slower in the brain (Ridley & Cavanagh, 1969b). As with rejection of solid grafts at other sites, cellular rather than humoral mechanisms seem to be responsible, since rejection can be prevented by ALS therapy (Ridley, 1970a, b).…”