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; Vascul…