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.

Inhalt
I Embryology of the Male Reproductive Tract.- Embryology of the Testis.- Hormonal Factors in the Development of the Male Genital System.- The Relationship Between Differentiation of the Testicle, Genital Ducts and External Genitalia in Fetal and Postnatal Life.- Heteroplastic Gonaduct-Testes Combinations: A Biochemical Outlook.- II Histology of the Testis.- Dynamics of Human Spermatogenesis.- Electron Microscopy of the Human Seminiferous Tubules.- Fine Structure of Testicular Interstitial Cells in Humans.- Histology of the Human Testis from Neonatal Period to Adolescence.- III Cytogenetics of Spermatogenesis.- Morphological Aspects of Meiosis and Their Genetical Significance.- Ultrastructure and Histochemistry of the Nucleus During Male Meiotic Prophase.- The Cytogenetics of the Male Germ Cells and the Testis in Mammals.- Chromosome Studies on Testicular Cells of Subfertile Men.- IV Regulation of Testicular Function.- Section 1: Role of the Hypothalamus.- Mechanism of Action of FSH and LH Releasing Factors.- Hypothalamic Control of Gonadotropin Secretion in the Male.- Purification and Chemistry of Gonadotropin Releasing Factors.- Further Studies on Mechanism of Action of Luteinizing Hormone Releasing Factor Using In Vivo and In Vitro Techniques.- Section 2: Testicular-Pituitary Interrelationship.- Investigations Into the Feed-Back Mechanism Between Spermatogenesis and Gonadotropin Level in Man.- The Role of FSH, ICSH, and Endogenous Testosterone During Testicular Suppression by Exogenous Testosterone in Normal Men.- Section 3: Gonadotropins, Purification and Measurement.- Use of Standards in Gonadotropin Assays.- Preparations and Biological Characteristics of HMG Preparations Used Clinically.- Plasma FSH and LH Measured by Radioimmunoassay in Normal and Pathologic Conditions in Men.- Section 4: Metabolic Effects of Gonadotropins.- Early Effects of FSH upon Testicular Metabolism.- Radioautographic Studies of Protein Synthesis in Cells of the Seminiferous Epithelium.- Studies of Spermatogenesis and Steroid Metabolism in Cultures of Human Testicular Tissue.- Section 5: Influence of Gonadotropins on Testicular Functio.- Effect of Gonadotropins on the Seminiferous Tubules of the Immature Testis.- Ultrastructural and Chemical Effects of LH upon the Seminiferous Tubule.- Biologic Effect of Human Pituitary Luteinizing Hormone and Human Chorionic Gonadotropin.- The Effect of Gonadotropins on the Prepubertal Testis.- V Testicular Steroidogenesis.- Steroid Secretion by the Human Testis.- Testosterone Plasma Levels in Normal and Pathological Conditions.- Relation of In Vitro Metabolism of Steroids in Human Testicular Tissue to Histologic and Clinical Findings.- Subcellular Structure and Synthesis of Steroids in the Testis.- VI Non-Hormonal Factors Influencing Sperm Production and Transport.- The Biochemical Characteristics of Spermatozoa and Seminal Plasma.- The Significance of Deviations in Human Sperm Morphology.- Pharmacological Studies on the Testicular Capsule in Relation to Sperm Transport.- Effect of Gonadotropins and Androgens on Fructose and Citric Acid of Seminal Fluid.- Immunological Aspects of Male Infertility.- VII Gonadotropin Therap.- Section 1: Treatment of Hypopituitarism.- Effects of HCG, HMG, HLH, and HGH Administration on Testicular Function.- Effect of Urinary FSH and LH on the Testicular Function in Hypogonadal Patients.- The Effects of Urinary Gonadotropins Following Hypophysectomy and in Hypogonadotropic Eunuchoidism.- Section 2: Treatment of Adult Seminiferous Tubular Failure.- Assessment of Gonadotropin Therapy in Infertile Males.- Assessment of Gonadotropin Therapy in Male Infertility.- Assessment of Gonadotropin Therapy in Male Infertility.- Concluding Remarks.