This volume describes the proceedings of the Workshop Conference on The Human Testis which was held at Positano, Italy, April 23-25, 1970. The format of the book has been arranged according to topics discussed during the Conference. Each chapter includes individual contributions followed by discussion. Thus, this volume provides a current critical evaluation of the subjects discussed. The Editors assume responsibility for any shortcomings and wish to thank all par~ ticipants for their unprecedented cooperation in making this publi­ cation possible. The Editors are indebted to Miss Barbara Martin for her able secretarial and administrative assistance and to Mrs. Griff T. Ross who supervised the secretarial staff during the conference. Rec­ ognition is also due to Mrs. M. Flack for editorial assistance. The Workshop Conference could not have taken place but for the Serono Foundation, which supported this Meeting as well as the pub­ lication of the Proceedings of this Workshop. The physical as well as the technical arrangements were under the careful direction of Mr. Cesare Florimonte of the Serono Foundation. The support pro­ vided by the Serono Foundation is another proof of its generosity in stimulating scientific exchanges and a demonstration of its con­ tinuous efforts to support basic and applied studies in the field of human reproduction. We express our thanks to our Publisher, Plenum Press, for their fine cooperation and for ensuring the rapid publication of this vol­ ume.