Changes

}}</ref> The two layers of the foreskin contain [[lymph]] between them to allow lubricated, frictionless [[gliding action]]. The skin ends just behind the [[glans penis]] but folds forward to cover it, this forming the [[preputial sac]] and, if long enough, the [[acroposthion]]. The moist [[preputial sac]] may harmlessly collect oil-bearing [[smegma]], which is helpful in preventing dermatitis.<ref name="birley1993">{{REFjournal