• Protection: Just as the eyelids protect the eyes, the foreskin protects the glans and keeps its surface soft, moist, and sensitive. It also maintains optimal warmth, pH balance, and cleanliness. The glans itself contains no sebaceous glands-glands that produce the sebum, or oil, that moisturizes our skin. The foreskin produces the sebum that maintains proper health of the surface of the glans.

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  Immunological Defense: The mucous membranes that line all body orifices are the body's first line of immunological defense. Glands in the foreskin produce antibacterial and antiviral proteins such as lysozyme. Lysozyme is also found in tears and mother's milk. Specialized epithelial Langerhans cells, an immune system component, abound in the foreskin's outer surface. Plasma cells in the foreskin's mucosal lining secrete immunoglobulins, antibodies that defend against infection.

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  Erogenous Sensitivity: The foreskin is as sensitive as the fingertips or the lips of the mouth. It contains a richer variety and greater concentration of specialized nerve receptors than any other part of the penis. These specialized nerve endings can discern motion, subtle changes in temperature, and fine gradations of texture.

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  Coverage During Erection: As it becomes erect, the penile shaft becomes thicker and longer. The double-layered foreskin provides the skin necessary to accommodate the expanded organ and to allow the penile skin to glide freely, smoothly, and pleasurably over the shaft and glans.

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  Self-Stimulating Sexual Functions: The foreskin's double-layered sheath enables the penile shaft skin to glide back and forth over the penile shaft. The foreskin can normally be slipped all the way, or almost all the way, back to the base of the penis, and also slipped forward beyond the glans. This wide range of motion is the mechanism by which the penis and the orgasmic triggers in the foreskin, frenulum, and glans are stimulated.

Sexual Functions in Intercourse: One of the foreskin's functions is to facilitate smooth, gentle movement between the mucosal surfaces of the two partners during intercourse. The foreskin enables the penis to slip in and out of the vagina nonabrasively inside its own slick sheath of self-lubricating, movable skin. The female is thus stimulated by moving pressure rather than by friction only, as when the male's foreskin is missing.