The Thymus

1 Introduction - Historical Background.- 2 Anatomy and Embryology of the Thymus.- 2.1 Embryology.- 2.2 Normal Anatomy.- 2.3 Involution.- 3 Immunologic Function of the Thymus.- 3.1 Historical Overview.- 3.2 T Cell Molecules in Antigen Recognition.- 3.3 Ontogeny of T Cells.- 3.4 Cellular Selection in the Thymus.- 3.5 Clinical Aspects.- 3.6 Summary.- 4 Imaging Procedures for Visualization of the Thymus.- 4.1 Plain Film Diagnostics E.Walter and E.Willich.- 4.2 Conventional Tomography.- 4.3 Ultrasonography.- 4.4 Computed Tomography.- 4.5 Magnetic Resonance Imaging W.R.Webb and G.deGeer.- 4.6 Nuclear Medicine E.Walter and E.Willich.- 4.7 Esophagography.- 4.8 Angiography.- 4.9 Obsolete Methods.- 4.10 Supplementary Procedures (Mediastinography, Bronchoscopy, Bronchography) E.Willich.- 5 Diagnostic Imaging of the Normal Thymus.- 5.1 Conventional Diagnostics in Children E.Willich and E.Walter.- 5.2 Ultrasonography.- 5.3 Computed Tomography E.Walter.- 5.4 Magnetic Resonance Imaging W.R.Webb and G.deGeer.- 5.5 Invasive Procedures (Pneumomediastinography, Arteriography, Phlebography) E.Walter.- 5.6 Measurement of the Size of the Thymus E.Willich.- 6 Acute and Stress-Induced Involution of the Thymus.- 6.1 Acute Endogenous Involution of the Thymus.- 6.2 Exogenous Involution of the Thymus: the Steroid Test.- 6.3 Transplacental Influence of Steroids on the Premature Infant's Thymus.- 7 Developmental Abnormalities of the Thymus.- 7.1 Aplasia, Hypoplasia, and Dysplasia E.Willich and E.Walter.- 7.2 Dystopia.- 7.3 Persistent Thymus E.Willich.- 7.4 Hyperplasia.- 8 Tumors of the Thymus.- 8.1 Introduction E.Walter.- 8.2 Epithelial Tumors of the Thymus.- 8.3 Carcinoid Tumors of the Thymus.- 8.4 Thymic Involvement in Malignant Lymphomas and Leukemia E.Willich and E.Walter.- 8.5 MesenchymalTumors (Thymolipoma) E.Walter.- 8.6 Germ Cell Tumors and Teratomas E.Walter.- 8.7 Rare Tumors of the Thymus.- 8.8 Metastases to the Thymus.- 9 Tumor-like (Nonneoplastic) Conditions of the Thymus and/or Mediastinum.- 9.1 Thymogenic Cysts.- 9.2 Hydatidosis of the Thymus.- 9.3 Tuberculoma of the Thymus.- 9.4 Histiocytosis X of the Thymus.- 10 Trauma and Hemorrhage of the Thymus.- 10.1 Trauma.- 10.2 Hemorrhage.- 11 Thymus and Myasthenia Gravis.- 11.1 Definition of Myasthenia Gravis H.Wlethölter.- 11.2 Clinical Manifestation.- 11.3 Associated Thymic Changes.- 11.4 Pathogenesis.- 11.5 Autoimmune Origin.- 11.6 Diagnosis.- 11.7 Treatment H.Wlethölter.