Main description:

This monograph brings together our work concerning the relationships be tween the hypothalamus, pituitary and testis. The studies span approximate ly a decade of collaborative work. Over this period our contributions and those of many others have advanced greatly our understanding of many aspects of male reproductive biology. This monograph attempts to survey these developments and to highlight many unresolved issues. It also provides an opportunity to demonstrate the value of investigations which relate bio chemical to structural parameters and to illustrate the importance of animal studies in elucidating biological principles with clinical applications. The reverse is also important since the pathophysiology of human disorders of ten provides insight into hitherto unsuspected basic mechanisms. In any rapidly expanding field it is difficult to stop revising and extending a manuscript. It is equally difficult to quote every reference in the field but we trust that those of significance have not been omitted. Some of our former students have collaborated with us as co-authors in producing this monograph. It is equally important to recognise the contributions of our other former students and colleagues who have physically participated in the studies and without whose intellectual contributions a number of concepts would not have been elucidated. Their work is acknowledged in the text of the monograph and the extensive list of references.

Contents:

1 Patterns of Secretion and Metabolism of the Gonadotrophic Hormones.- 1.1 Assay Methods.- 1.1.1 Human FSH, LH and Prolactin.- 1.1.2 Animal Gonadotrophins.- 1.2 Patterns of LH and FSH Secretion in Normal Men.- 1.3 Metabolic Clearance and Gonadotrophin Secretion Rates in Normal Men.- 1.3.1 MCR and Production Rate of LH.- 1.3.2 MCR and Production Rate of FSH.- 1.3.3 Initial Clearance of Gonadotrophin Subunits.- 1.3.4 Effect of Renal Disease on MCR.- 1.4 Summary.- 2 Control of FSH and LH Secretion.- 2.1 Sites of Production of FSH and LH.- 2.2 Hypothalamic Influences on FSH and LH Secretion.- 2.3 Influence of Testicular Feedback.- 2.3.1 Feedback Control of LH.- 2.3.2 Feedback Control of FSH.- 2.4 Assays for Inhibin.- 2.4.1 Modified Steelman-Pohley Bioassay.- 2.4.2 Bioassays Using Castrate Rams.- 2.4.3 Bioassays In Vivo Using Rodents.- 2.4.4 In Vitro Bioassays for Inhibin.- 2.5 Assay Specificity.- 2.6 Sources of Inhibin.- 2.7 Evidence for Inhibin from Immunisation Studies.- 2.8 Characteristics and Mode of Action of Inhibin.- 2.9 Physiological Implications of Inhibin.- 2.10 Summary.- 3 Pituitary Testicular Axis During Pubertal Development.- 3.1 Studies in Men.- 3.1.1 Changes During Fetal Life.- 3.1.2 Changes in the Newborn.- 3.1.3 Changes During Childhood and Adolescence.- 3.1.4 Pituitary Responses to LHRH.- 3.2 Studies in Rats.- 3.2.1 Changes in LH, FSH and Testosterone Concentrations with Age.- 3.2.2 Relationship Between Age and Hormonal Levels.- 3.2.3 Changes in Testicular Histology with Age.- 3.2.4 Significance of Hormonal Changes in the Developing Rat.- 3.3 Studies in Rams.- 3.3.1 Changes in FSH, LH, Prolactin and Testosterone Concentrations with Age.- 3.3.2 LH, FSH and Testosterone Responses to LHRH with Age.- 3.3.3 Changes in Testicular Histology with Age.- 3.3.4 Significance of Hormonal Changes.- 3.4 Overall Comments.- 4 Changes in the Pituitary-Testicular Axis with Age.- 4.1 Introduction.- 4.2 Methods.- 4.2.1 Testing the Pituitary-Testicular Axis.- 4.2.2 Selection of Subjects.- 4.2.3 Statistical Methods.- 4.3 Summary of Results.- 4.3.1 Virility, Testicular Size and Histology.- 4.3.2 Gonadotrophin and Sex Hormone Levels.- 4.3.3 Metabolic Clearance and Production Rates of Sex Steroids.- 4.3.4 Dynamic Tests of Gonadotrophin and Testosterone Secretion.- 4.4 Significance of Senescent Testicular Degeneration.- 4.4.1 Mechanism of Hormone Changes with Age.- 4.4.2 Further Studies.- 4.4.3 Aetiology of Testicular Damage.- 4.5 Clinical Relevance.- 4.6 Summary.- 5 Spermatogenesis and the Sertoli Cell.- 5.1 Spermatogenesis.- 5.1.1 The Spermatogenic Cycle.- 5.1.2 Kinetics of the Spermatogenic Process.- 5.1.3 Duration of Spermatogenesis.- 5.1.4 Requirements for Quantitation of Spermatogenesis.- 5.2 The Sertoli Cell.- 5.2.1 Morphological Characteristics.- 5.2.2 Nucleus.- 5.2.3 Cytoplasm.- 5.2.4 Inter-Sertoli Cell Junctions.- 5.2.5 Sertoli Cell Maturation.- 5.2.6 Secretory Products.- 5.2.6.1 Seminiferous Tubule Fluid.- 5.2.6.2 Androgen-Binding Protein.- 5.2.6.3 Inhibin.- 5.2.6.4 Plasminogen Activator.- 5.2.6.5 Other Secretory Products.- 5.2.7 Steroidogenic Activity.- 5.2.8 Hormonal Regulation of Sertoli Cell Function.- 5.2.9 Actions of FSH on the Sertoli Cell.- 5.2.10 Effects of Androgen on the Sertoli Cell.- 5.2.11 Biochemical Changes Associated with Sertoli Cell Maturation.- 6 Leydig Cell Function.- 6.1 Introduction.- 6.2 Morphology of the Leydig Cell.- 6.3 Steroid Biosynthesis and Secretion.- 6.4 Regulation of Leydig Cell Function.- 6.5 Hormonal Regulation of LH Receptors.- 6.5.1 LHRH and Leydig Cell Function.- 6.6 Leydig Cells and Spermatogenesis.- 6.7 Androgens in Blood.- 6.8 Abnormalities of Leydig Cell Function.- 6.8.1 Congenital Disorders.- 6.8.2 Acquired Disorders.- 6.8.2.1 Cirrhosis of the Liver.- 6.8.2.2 Chronic Renal Failure.- 6.8.2.3 Age.- 6.8.3 Testicular Disorders.- 7 The Effect of Testicular Damage on Sertoli and Leydig Cell Function.- 7.1 Introduction.- 7.2 Spermatogenic Damage and the Control of FSH Secretion.- 7.3 Sertoli Cell Function and Testicular Damage.- 7.4 Luteinising Hormone, Testosterone and Spermatogenic Damage.- 7.5 Leydig Cell Structure and Spermatogenic Damage.- 7.6 Leydig Cell Function and Testicular Damage.- References.