Vesicoureteral Reflux.- A. Definition of Reflux.- B. Anatomy of the Ureterovesical Junction.- I. Contribution of the Ureter and Trigone to the Formation of the Ureterovesical Junction.- II. The Vesical Component of the Ureterovesical Valve.- 1. The Mucosal Layer.- 2. The Inner Longitudinal Muscle Layer.- 3. The Middle Circular Muscle Layer.- 4. The Outer Longitudinal Muscle Layer.- C. Innervation.- D. Physiology of the Ureterovesical Valve.- I. The Effect of Interrupting the Anatomical Continuity between the Ureter and the Trigone.- II. The Effect of Cutting the Nerves that Supply the Trigonal Muscle.- III. The Effect of Active Contraction of the Trigone on the Resistance of the Intravesical Ureter.- IV. The Effect of Active Contraction of the Trigone in Tightening and Occluding the Intravesical Ureter during Voiding.- E. Pathology of the Ureterovesical Junction.- I. Structural Changes at the Ureterovesical Junction.- 1. Conditions in which the Ureteral Hiatus Moves Downward in Relationship to the Ureteral Orifice.- 2. Conditions in which the Ureteral Orifice Moves Upward in Relation to the Ureteral Hiatus.- II. The Effect of Vesical Edema on the Ureterovesical Junction.- III. Congenital Anomalies of the Ureter.- IV. Maturation of the Intravesical Ureter.- V. Concept of the Marginally Competent Ureterovesical Junction.- F. Classification of Reflux by Etiology.- I. Reflux Due to Trigonal Weakness.- II. Reflux Due to Obstruction at or below the Bladder Neck.- III. Reflux Due to Neurogenic Vesical Disease.- IV. Reflux Due to Edema of the Bladder Wall.- V. Reflux Due to Congenital Anomalies.- VI. Reflux Due to Iatrogenic Causes.- G. Etiology of Nonocclusive Ureteral Dilatation (Megaloureter).- I. Factors that Increase the Volume of Urine in the Ureter.- 1. Dilation of the Renal Pelvis and Ureter by Forced Intake of Fluids.- 2. Dilation of the Upper Urinary Tract Due to Diabetes Insipidus.- 3. Dilation of the Pelvis of a Kidney Forced to Increase its Output after Unilateral Nephrectomy.- 4. Reflux as a Cause of Ureteral Overfilling.- II. Emptying Capacity of Various Areas of the Ureter.- III. Reflux and the Ureteropelvic Junction.- IV. Reflux and the Ureterovesical Junction.- H. Incidence of Reflux.- I. High Incidence of Reflux in Children with Urinary Tract Infection.- II. Demonstration of Reflux in Adults with Nonobstructive Pyelonephritis.- I. Effects of Reflux.- I. The Role of Reflux in Obstruction at the Ureteropelvic Junction.- II. The Kidney with Chronic Pyelonephritis.- III. The Atrophic Kidney with Chronic Pyelonephritis.- IV. The Normal Kidney.- V. Reflux as the Cause of Pyelonephritis of Pregnancy.- VI. Role of Reflux in the Perpetuation of Urinary Tract Infection.- VII. Miscellaneous.- J. The Role of the Ureterovesical Junction in the Pathogenesis of Pyelonephritis.- I. Childhood.- II. The Teenage Period.- III. The Adult Period.- IV. Prostatic Period.- K. The Treatment of Reflux and its Complications.- I. Medical Treatment.- II. The Surgical Correction of Reflux.- 1. Types of Operation.- 2. Results of Operation.- 3. Indications for Operation.- a) The Severity of the Reflux.- b) The Presence of Saccules.- c) The Severity of the Clinical Course.- d) The Conditions of the Kidneys.- e) The Age of the Patient.- References.- Anomalies of the Kidney.- I. Agenesis.- a) Bilateral Renal Agenesis.- b) Solitary Pelvic Kidney.- II. Hypoplasia.- a) Unilateral.- b) Bilateral.- III. Cystic Disease.- a) Simple (Solitary) Cysts.- b) Multiple Cysts of the Kidney.- c) Multilocular Cysts.- d) Polycystic Kidney Disease.- e) Peripelvic Cysts.- IV. Fusion Anomalies of the Kidney.- a) Horseshoe Kidney.- b) Unilateral Fused Kidney.- c) Fused Pelvic Kidney.- V. Ectopia of the Kidney.- 1. Introduction.- 2. Classification.- a) Simple Ectopy.- b) Bilateral Ectopia.- c) Crossed Renal Ectopia.- d) Ectopic Pelvic Kidney.- e) Thoracic Kidney (Congenital Superior Ectopia).- VI. Anomalies of Rotation.- 1. Introduction.- 2. Embryology.- 3. Incidence.- 4. E