Changes

When the anatomically complete penis thrusts in the vagina, it does not slide, but rather glides on its own 'bedding' of movable [[skin]], in much the same way that a turtle's neck glides in and out of the folder layers of [[skin]] surrounding it. The underlying corpus cavernosa and corpus spongiosum slide within the penile [[penile skin]], while the [[skin]] juxtaposed agaist the vaginal wall moves very little. This sheath-within-a-sheath alignment allows penile movement, and vaginal and penile stimulation, with minimal friction or loss of secretions. When the penile shaft is withdrawn slightly from the vagina, the foreskin bunches up behind the corona in a manner that allows the tip of the foreskin which contains the highest density of fine-touch neuroreceptors in the penis to contact the corona of the glans which has the highest concentration of fine-touch receptors on the glans. This intense stimulation discourages the penile shaft from further withdrawal, explaining the short thrusting style that women noted in their unaltered partners.<ref name="ohara1999" />

As stated, circumcision removes 33-50% of the penile [[penile skin]]. With this [[skin]] missing, there is less tissue for the swollen corpus cavernosa and corpus spongiosum to slide against. Instead the [[skin]] of the circumcised penis rubs against the vaginal wall, increasing friction, abrasion and the need for artificial lubrication. Because of the tight penile [[penile skin]], the corona of the glans, which is configured as a one-way valve pulls the vaginal secretions from the vagina when the shaft is withdrawn.<ref name="ohara1999" />