Sexual Mechanosensitivity: Age-Related Changes in the Innervation of the Human Prepuce.

Background/Objectives: The male prepuce that covers the glans penis is richly innervated by low-threshold mechanoreceptors, which form cutaneous end-organ complexes (Meissner, Pacinian and Ruffini corpuscles) and mucous end-organ complexes (especially Krause-like corpuscles). The mechanosensory inputs from these formations are the beginning for spinal reflexes that regulate movements of intercourse and erection and, therefore, are required for sexual function. The study was aimed at analyzing the age-dependent changes in prepuce innervation. Methods: Here we used immunohistochemistry to investigate whether the innervation of the male prepuce undergoes age-dependent changes, analyzing subjects aged 4 months to 61 years. Results: Abundant Meissner corpuscles and Krause-like corpuscles were regularly found whose morphology, size, and topography were variable and were not correlated with age; however, Ruffini's and Pacinian corpuscles were scarcely observed. The earliest evidence of Meissner corpuscles was observed at 4 months, and thereafter they undergo significant age-dependent variations in density. Until the age of 20 years increases progressively, remains stable until 40 years, and then the density decreases. Meissner's corpuscle index paralleled that of density. Regarding Kause-like corpuscles already resemble the skin of 4-month-old subjects and from the age of 3 years they can be identified at all ages. Its density significantly increased until 10 years and then remained stable. Conclusions: Present results state that the mechanosensory innervation of the human foreskin reaches its maximum value around the age of 20, remains stable during adulthood and decreases with maturity. These findings contribute to a more complete understanding of foreskin innervation and add to the scientific knowledge base surrounding the potential harm of removing a richly innervated structure.