The Development of the Perineum in the Human

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 Subject Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 1 Introduction The developmental steps which lead to the formation of the human perineum seem firmly established (Arey 1965; Hamilton and Mossman1972; Moore and Persaud 1998; Wartenberg 1993; Sadler 1995; Larsen 1997). They form the base for the evaluation of the pathogenesis of a great variety of complicated and often serious malformations which occur in this region. This concept has, however, been challenged by the results of an investigation into the n- mal and abnormal development of the anorectum in pig (van der Putte and Neeteson 1983, 1984; van der Putte 1986). Observations revealed that at least in pig, a major element in current ideas about the early development of the perineum, namely the process by which the original simple cloaca is sub- vided into a urogenital and anal part is incorrect, while additional obser- tions strongly suggested that the same may be true for ideas about female and male sexual transformation. A preliminary investigation in human - bryos gave similar indications (van der Putte 1986). The data supported e- lier critical findings (Politzer 1931, 1932; Wijnen 1964; Ludwig 1965) which have apparently been ignored, possibly because they seemed to hinder the understanding of the pathogenesis of congenital malformations such as - perforate anus and hypospadias.

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.