many would regard his outstanding contribution to be his ability to see the coherent biological process behind reproduction, where his work is an outstanding example of translational research from experimental studies to clinical investigation of andrological disorders. his understanding of human fertility and infertility lead him to carry out many highly original animal studies that were necessary to understand the human problems, including the role of androgens in fetal life for the later development of the reproductive system and cell-cell interactions within it. the oestrogen hypothesis () is a citation classic which developed into the hypothesis of early androgen deprivation during fetal life, illustrated by experiments using phthalates (a ubiquitous component of plastic products). while he was not the first to show effects of phthalates on the fetal rat testis, he saw its broader significance for human reproduction – and again he built a bridge here between basic science and clinical research.