Three-dimensional reconstruction of the anal striated musculature in a human fetus

Conflicting opinions in the recent literature indicate that the morphologic al organization and function of the anorectal continence organ has, up to n ow, not been clearly understood. But a clear imagination of the spatial arr angements of this compound muscle system is of clinical relevance for the p ediatric surgeon performing reconstructive surgery. We analyzed 18-mum sect ions of the pelvic region of 4 human fetuses in order to describe the indiv idual components of this muscle complex. A series of 630 Azan-stained secti ons was the base for the computer-assisted 3D reconstruction of the levator ani and the external sphincter complex in a male human fetus (14th week p. c.). In this context, special attention was paid to the intermediate muscle layer of the puborectalis which develops ventrally from the funnel-shaped levator ani and joins the tripartite ring system of the sphincter muscle do rsally. Our findings lead to a clear imagination of the spatial arrangement of this intermediate layer and characterize the anorectal muscle complex a s an integrated ensemble in which the puborectalis holds a key position. Co pyright (C) 2001 S.KargerAG, Basel.