Preliminary insights into intratesticular and intraepididymal administration of eugenol: histological alterations and impact on sperm motility in Wistar rats

Renner Philipe Rodrigues Carvalho; Iara Magalhaes Ribeiro; Camilo Ramirez-Lopez; Tayná Bolsam da Silva; Alex Filipe Ramos de Sousa; Arabela Guedes de Azevedo Viana; Victor de  Medeiros; Ana Carolina Marta Trindade; Thanyanne Rafaela de Morais  Ferreira; Luiz Otávio Guimaraes  Ervilha; Mariana Machado-Neves

doi:10.1590/1984-3143-AR2025-0026

SHORT COMMUNICATION

Preliminary insights into intratesticular and intraepididymal administration of eugenol: histological alterations and impact on sperm motility in Wistar rats

Renner Philipe Rodrigues Carvalho; Iara Magalhaes Ribeiro; Camilo Ramirez-Lopez; Tayná Bolsam da Silva; Alex Filipe Ramos de Sousa; Arabela Guedes de Azevedo Viana; Victor de Medeiros; Ana Carolina Marta Trindade; Thanyanne Rafaela de Morais Ferreira; Luiz Otávio Guimaraes Ervilha; Mariana Machado-Neves

http://dx.doi.org/10.1590/1984-3143-AR2025-0026 Anim Reprod, vol.23, n2, e20250026, 2026

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Abstract

This study assessed the histopathological and functional consequences of single bilateral intratesticular (InT; 200, 20, and 10 mg) and intraepididymal (InE; 50, 5, and 2.5 mg) eugenol administration in Wistar rats. Animals were monitored for up to 60 days, and testicular and epididymal tissues were examined for morphological alterations and sperm motility impairment. Both administration routes induced marked structural damage to the male reproductive tract. InT application led to progressive degeneration of the seminiferous epithelium, tubular atrophy, interstitial fibrosis, and focal mineralization, accompanied by reductions in both Leydig cell volumetric proportion and nuclear volume, hallmarks of impaired spermatogenesis and disrupted lumicrine signaling. In contrast, InE administration caused epithelial necrosis, intraluminal cellular debris accumulation, fibrotic remodeling, and ductal occlusion, ultimately leading to complete loss of sperm motility due to impaired maturation and obstructed transport. Although no overt systemic toxicity was observed, the findings indicate that local eugenol delivery exerts direct cytotoxic effects and promotes irreversible tissue remodeling. These results highlight eugenol’s potential as a chemical sterilant and reinforce the need for further studies to evaluate the reversibility of reproductive damage, inflammatory sequelae, and interspecies variability in toxicological responses.

Keywords

chemical castration, Syzygium aromaticum, toxicology, morphology

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Submitted date:
03/12/2025

Accepted date:
12/11/2025

Preliminary insights into intratesticular and intraepididymal administration of eugenol: histological alterations and impact on sperm motility in Wistar rats

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