There are controversies with respect to the location, number, and function
of the transverse folds of the rectum (TFR), probably because their physioa
natomic aspects have not been fully investigated. The purpose of this commu
nication was to study the anatomic and histologic structure of the TFR aimi
ng at elucidation of their function in the light of their structure. The TF
R were studied morphologically and histologically in 18 cadavers (10 male,
8 female) with a mean age of 36.6 +/- 10.4 (SD) years. Barium enema studies
were also performed in 36 volunteers (20 male, 16 female; mean age 38.6 +/
- 15.2 [SD] years). The number of TFR varied, the commonest findings being
two and three. Ln a few cases, TFR were absent or exceeded three in number.
Most folds extended beyond the middle of the rectal lumen; a few were narr
ow. They were thick at the base and tapered gradually. Microscopically, the
TFR contained circular and longitudinal smooth muscle fibers; they were ra
rely purely mucosal. TFR varied in location dividing the rectum into compar
tments: an alternating side-to-side arrangement allows for a wavy movement
of the stool in the rectum. The wavy movement, compartmental division, and
the shelving action of the TFR are suggested to retard stool movement in th
e rectum so as to allow time for fecal sampling (stool or gas) and for impu
lses to reach the conscious level to decide whether or not to defecate. Fur
ther studies are needed to investigate the role of the TFR in clinical prac
tice. (C) 2001 Wiley-Liss. Inc.