RECENTLY DAN PERCY ASKED FOR SUGGESTIONS ON WHERE TO FIND INFO ON WHY EMBRYOS ARE NOT IMMUNOLOGICALLY REJECTED BY THE MOTHER. IN CERTAIN ANIMALS (I.E. RUMINANTS) A GOOD DEAL OF INFORMATION HAS BEEN GENERATED. I SUGGEST YOU READ ARTICLES BY: P.J. HANSEN; R.M. ROBERTS; F.W. BAZER; W.W. THATCHER; GOOD READING!