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**Therefore the most distal part of the rectum is retroperitoneal.
 
**Therefore the most distal part of the rectum is retroperitoneal.
 
***This distal, retroperitoneal part is directly attached to the vagina in the female and to the urethra in the male.
 
***This distal, retroperitoneal part is directly attached to the vagina in the female and to the urethra in the male.
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***The retroperitoneal space is filled with soft tissue rich in fat.
 
*The '''anal canal''' joins the bowel to the exterior.
 
*The '''anal canal''' joins the bowel to the exterior.
 
**This is a short passage derived from the proctodeum (formed by invagination of the surface ectoderm).
 
**This is a short passage derived from the proctodeum (formed by invagination of the surface ectoderm).
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**Before joining the anal canal, the rectum becomes dilated to form the ''rectal ampulla''.
 
*At the rectoanal junction, the lumen is constricted by longitudinal folds in the mucosa.
 
*At the rectoanal junction, the lumen is constricted by longitudinal folds in the mucosa.
 
**These are normally pressed together to occlude the lumen.
 
**These are normally pressed together to occlude the lumen.
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