The study found that human penile innervation develops in distinct fetal stages and shows region-specific patterns in adults, with the frenular delta the triangular ventral area where the glans meets the shaft containing higher densities of nerve bundles and sensory corpuscles than other regions, including the glans.
Researchers conducted the work to address longstanding gaps in detailed knowledge of penile neuroanatomy. Penile sexual sensation depends on complex neural structures whose development and precise organization had not been fully mapped at the cellular level, particularly in relation to surgical practices such as circumcision.
Before this study, standard anatomical descriptions and textbooks typically identified the glans as the primary site of male genital sensation. Earlier work, including prior studies by the same research group, had begun to document dense innervation in the prepuce and ventral penis but lacked a complete ontogenetic (developmental) account from early fetal stages through adulthood or a systematic comparison of sensory structures across penile regions.
The researchers examined formalin-fixed, paraffin-embedded tissue from 30 fetal specimens (gestational ages 8–24 weeks) and 14 adult cadaveric penises (donor ages 45–73 years). They prepared serial sections in multiple planes (transverse, sagittal, coronal) and applied routine histological stains plus a panel of immunohistochemical markers specific to neural elements, including axons (neurofilament, PGP9.5, NSE), Schwann cells (S100, SOX10), sensory corpuscles (various markers for Meissner, Krause, Pacinian, genital corpuscles and others), and autonomic nerves. Sections were examined under light microscopy to map nerve pathways, quantify relative densities semiquantitatively, characterize sensory corpuscle types and their molecular profiles, and trace developmental changes.
Results showed two clear phases of fetal development. In the pre-corpuscular stage (8–16 weeks), there was axonal hyperinnervation with abundant intraepithelial nerve fibres, especially on the ventral surface. In the corpuscular stage (17–24 weeks), Pacinian corpuscles appeared and targeted neural pruning occurred. In adult tissue, nerve bundles and sensory corpuscles were not evenly distributed: transverse sections revealed a markedly higher concentration of nerve bundles and clustered corpuscular receptors (up to 17 densely packed in a small frenular area) in the frenular delta and adjacent ventral prepuce compared with the dorsolateral glans lamina propria, where such clusters were absent and corpuscles occurred more sparsely or in isolation. The frenular delta received overlapping contributions from perineal and dorsal penile nerve branches. Sensory corpuscles across all regions shared consistent immunohistochemical profiles, but their density and clustering differed by location. The preputial dartos and associated vasculature showed dense autonomic innervation; a previously under-described superficial layer of the glans tunica albuginea was also identified.
The researchers themselves concluded that the findings provide the first comprehensive ontogenetic framework of penile innervation and document the frenular delta’s unique features. “Although the classical description in Guyton and Hall positions the glans as the primary source of penile sexual afferent signals, our study…supports a revised paradigm in which the distal ventral penile surface, particularly the frenular delta and surrounding region, constitutes the principal neurological locus of penile sexual sensation,” they wrote. They noted that the data “inform current debates on penile circumcision and neurotomy” and emphasised the need for surgical care to preserve frenular structures.
The study has limitations. It relied on cadaveric and fetal tissue only, with no postnatal samples from infancy through early adulthood, so intermediate developmental stages are unexamined. Fetal age estimates showed interindividual variation, and neural-density assessments were semiquantitative rather than fully quantitative. Alcohol-based fixation was used for some adult specimens, though antigen preservation was optimised. The work is purely anatomical and histological; it does not include functional testing of sensation in living individuals or clinical outcome data.
Reference
Cepeda-Emiliani A, Otero-Alén M, Suárez-Quintanilla J, Gándara-Cortés M, García-Caballero T, Gallego R, García-Caballero L. The sensory penis: A comprehensive immunohistological and ontogenetic exploration of human penile innervation. Andrology. 2026. https://doi.org/10.1111/andr.70118
