I. Current Views on Androgen Receptors and Mechanism of Androgen Action.- 1. Introduction.- 2. Effect of Androgens on Various Tissues.- 2.1. Androgen-Responsive Tissues.- 2.2. Effect on Secondary Sexual Organs.- 2.2.1. Macroscopical and Histological Responses.- 2.2.2. Biochemical Responses.- 2.3. Androgen-Mediated Template Activity of Isolated Nuclear Chromatin.- 2.4. Androgen Effects on Muscle, Bone Marrow and Erythropoiesis, Skin and Other Tissues.- 3. Uptake, Retention and Metabolism of Androgens in Responsive Tissues.- 3.1. Highly Responsive Tissues.- 3.2. DHT Formation in Responsive Tissues.- 3.3. Androgens in Slightly Responsive Tissues.- 4. Androgen Receptors.- 4.1. The Cytoplasmic Androgen Receptor.- 4.1.1. Extraction.- 4.1.2. Labeling.- 4.1.3. Properties of the Cytoplasmic Androgen Receptor.- 4.1.4. Physicochemical Parameters.- 4.1.5. Interconversion of the 810 S and 35 S Forms of the Cytoplasmic Receptor by Salt.- 4.1.6. Csllular Localization of the Cytoplasmic Receptor.- 4.1.7. Isolation and Purification of the Cytoplasmic Androgen Receptor.- 4.2. The Nuclear Androgen Receptor.- 4.2.1. Labeling.- 4.2.2. Isolation and Purification of Nuclei.- 4.2.3. Extraction of the Nuclear Receptor.- 4.2.4. Properties.- 4.2.5. Discriminatory Features of the Nuclear and Cytoplasmic Androgen Receptor.- 4.2.6. Origin of the Nuclear Androgen Receptor.- 4.3. Hypotheses.- 5. Androgen Receptor in Human Tissue.- 6. Occurrence of Multiple Steroid Hormone Receptors in Target Organs.- References.- II. Determination of Androgens by Competitive Protein-Binding Method and Radio-immunoassay.- 1. Competitive Protein-Binding Method.- 1.1. Principle.- 1.2. General Procedure for the Assay.- 1.3. Preparation of Steroid-Binding Proteins.- 1.4. Results.- 1.5. Precision.- 1.6. Specificity.- 1.7. Sensitivity.- 2. Radioimmunoassay.- 2.1. Requirements for Radioimmunoassay.- 2.2. Production of Antibodies.- 2.3. Purification of the Antiserum with RIVANOL.- 2.4. Titer.- 2.5. Specificity.- 2.6.l³F