Part 1: Introduction.- Part 2: Materials and Methods.- Part 3: Development of the Sexually Indifferent Perineum; Introduction; Observations, Pre-cloacal Perineum; Cloacal Perineum; Post-cloacal Perineum; Discussion; Cloacal Eminence; Cloaca and Allantois; Partition of the Mesonephric Ducts and Ureters; Division of the Cloaca; Urogenital Sinus; Anal Canal; Perineal Striated Musculature; Vascular System; Labioscrotal Swellings.- Part 4: Development of the Female Perineum; Introduction; Observations; Vagina; Transformation of the Urogenital Sinus into the Urethra and Vestibulum; Urethra; Vestibulum; Erectile Structures; Fascial Structures; Labia Majora; Anal Canal; Perineal Striated Musculature; External Perineum; Discussion; Vagina; Transformation of the Urogenital Sinus into the Urethra and Vestibulum; Urethra; Vestibulum; Labia Majora; Anal Canal; External Perineum.- Part 5: Development of the Male Perineum; Introduction; Observations; Urethra; Erectile Structures; Fascial Tissues; Perineal Septum; Penis, Prepuce, Preputial Sac and Frenulum; Scrotum; Anal Canal; Perineal Striated Musculature; External Perineum; Discussion; Urethra; Erectile Structures; Perineal Raphe, Septum, Body and Fasciae; Penis, Prepuce, Preputial Sac and Frenulum; Scrotum.- Part 6: Summary.- References.- Index.