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BMC veterinary research2025; 21(1); 682; doi: 10.1186/s12917-025-05137-5

Regional variations in the morphology of the efferent ductules: a histological perspective in rats, bulls, stallions, and boars.

Abstract: Infertility is a global concern in both humans and domestic animals, with male factors accounting for nearly half of all cases. Among male reproductive structures, the efferent ductules play a crucial but understudied role in fertility. These tubules connect the testis to the epididymis and are primarily responsible for luminal fluid reabsorption, a process essential for sperm concentration, maturation, and transport. This study aimed to provide a comparative morphological and histological characterization of the efferent ductules in four species-rats, bulls, stallions, and boars-focusing on regional variations (proximal, middle, and distal) and their potential functional implications. Results: Gross dissection and histological evaluation revealed a columnar epithelium composed of ciliated and nonciliated cells in all species. Comparative analysis identified species-specific differences in connective tissue composition, smooth muscle thickness, and epithelial dimensions. Proximal regions generally exhibited larger lumen diameters and lower epithelial heights, whereas distal regions showed increased ciliary height and, in some species, a greater presence of cytoplasmic granules, suggesting enhanced secretory or absorptive activity prior to sperm entry into the epididymis. Boars exhibited a particularly thick smooth muscle layer and abundant granules in the distal region. Morphometric measurements supported these observations, demonstrating consistent patterns of structural variation across species. Conclusions: The efferent ductules display complex, species-specific architecture and specialized regional features that likely contribute to their functional role in fluid reabsorption and sperm modification. These findings expand current knowledge of male reproductive morphology in domestic animals and highlight the need for further functional studies beyond rodent models to better understand fertility regulation in veterinary species.
© 2025. The Author(s).
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Publication Date: 2025-11-24 PubMed ID: 41287080PubMed Central: PMC12642179DOI: 10.1186/s12917-025-05137-5Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study examined the microscopic structure of the efferent ductules—a key part of the male reproductive system—in four species: rats, bulls, stallions, and boars.
  • It identified region-specific and species-specific differences in the tissue makeup that relate to how these ductules support sperm maturation, transport, and fertility.

Introduction to the Study

  • Infertility, affecting humans and domestic animals alike, often involves male reproductive issues, with nearly half of cases linked to male factors.
  • The efferent ductules connect the testis to the epididymis and are crucial for reabsorbing fluid from the sperm’s surrounding environment.
  • By removing excess fluid, the efferent ductules increase sperm concentration and help create the right conditions for sperm to mature and travel successfully towards fertilization.
  • Despite their importance, these ductules have been understudied, especially in domestic animals compared to rodents.
  • This research aimed to fill that gap by analyzing the morphology and histology of those ductules in rats, bulls, stallions, and boars.

Methodology

  • Gross dissection: The researchers physically isolated the efferent ductules from specimens of each species to observe their overall structure.
  • Histological evaluation: Tissue samples from proximal (near the testis), middle, and distal (near the epididymis) regions were prepared and examined under a microscope.
  • Comparison across species and regions focused on the epithelial cell composition, connective tissue, smooth muscle layers, and dimensions such as lumen diameter and epithelial height.

Key Findings

  • The epithelium lining the ductules was columnar with two types of cells:
    • Ciliated cells, which help move fluid and sperm through the ducts.
    • Nonciliated cells involved in absorption and secretion.
  • Species-specific differences included variations in:
    • Connective tissue composition, affecting structural support.
    • Thickness of the smooth muscle layer surrounding the ductules.
    • Size and shape of the epithelial cells and the lumen (the duct’s hollow interior).
  • Regional differences within each species:
    • Proximal regions generally had larger lumen diameters but shorter epithelial heights, indicating a design favoring fluid flow.
    • Distal regions showed increased ciliary height and more cytoplasmic granules in some species, implying enhanced secretory or absorptive activity as sperm prepare to enter the epididymis.
  • Boars were notable for particularly thick smooth muscle layers and abundant secretory granules in the distal region, suggesting a pronounced role in fluid manipulation and potentially sperm modification.
  • Morphometric data (quantitative structural measurements) supported these observations, confirming consistent patterns across species.

Implications and Conclusions

  • The detailed, species-specific differences in efferent ductule morphology suggest that these structures have evolved tailored functions to optimize fluid reabsorption and sperm quality for each animal.
  • The regional variations along the ductule indicate specialized zones with distinct physiological roles during sperm transport and maturation.
  • This study expands our anatomical and histological understanding of male reproductive organs beyond traditional rodent models to include important domestic species, which has implications for veterinary reproductive health and fertility management.
  • Future research should focus on exploring the functional consequences of these morphological features, perhaps examining how they relate to fertility outcomes and how they respond to environmental or hormonal influences.

Cite This Article

APA
Carvalho RPR, Silva KDP, Ramirez-Lopez CJ, Guimarães-Ervilha LO, Lima TI, Teixeira-Soares CM, de Azevedo Viana AG, Ribeiro IM, Morais-Santos M, Vergara JCM, Machado-Neves M. (2025). Regional variations in the morphology of the efferent ductules: a histological perspective in rats, bulls, stallions, and boars. BMC Vet Res, 21(1), 682. https://doi.org/10.1186/s12917-025-05137-5

Publication

BMC veterinary research
ISSN: 1746-6148
NlmUniqueID: 101249759
Country: England
Language: English
Volume: 21
Issue: 1
Pages: 682
PII: 682

Researcher Affiliations

Carvalho, Renner Philipe Rodrigues
  • Postgraduate Program in Veterinary Medicine, Department of Veterinary, Federal University of Viçosa, Viçosa, Brazil.
  • Laboratory of Structural Biology, Department of General Biology, Federal University of Viçosa, Av. P.H. Rolfs, S/N, DBG, ECS333, Campus Universitário, Viçosa, 36570-900, Brazil.
Silva, Kamilla Dias Paes
  • Postgraduate Program in Veterinary Medicine, Department of Veterinary, Federal University of Viçosa, Viçosa, Brazil.
  • Laboratory of Structural Biology, Department of General Biology, Federal University of Viçosa, Av. P.H. Rolfs, S/N, DBG, ECS333, Campus Universitário, Viçosa, 36570-900, Brazil.
Ramirez-Lopez, Camilo Jose
  • Laboratory of Structural Biology, Department of General Biology, Federal University of Viçosa, Av. P.H. Rolfs, S/N, DBG, ECS333, Campus Universitário, Viçosa, 36570-900, Brazil.
Guimarães-Ervilha, Luiz Otávio
  • Laboratory of Structural Biology, Department of General Biology, Federal University of Viçosa, Av. P.H. Rolfs, S/N, DBG, ECS333, Campus Universitário, Viçosa, 36570-900, Brazil.
Lima, Thaina Iasbik
  • Laboratory of Structural Biology, Department of General Biology, Federal University of Viçosa, Av. P.H. Rolfs, S/N, DBG, ECS333, Campus Universitário, Viçosa, 36570-900, Brazil.
Teixeira-Soares, Carlos Mattos
  • Postgraduate Program in Veterinary Medicine, Department of Veterinary, Federal University of Viçosa, Viçosa, Brazil.
de Azevedo Viana, Arabela Guedes
  • Laboratory of Structural Biology, Department of General Biology, Federal University of Viçosa, Av. P.H. Rolfs, S/N, DBG, ECS333, Campus Universitário, Viçosa, 36570-900, Brazil.
Ribeiro, Iara Magalhães
  • Postgraduate Program in Veterinary Medicine, Department of Veterinary, Federal University of Viçosa, Viçosa, Brazil.
  • Laboratory of Structural Biology, Department of General Biology, Federal University of Viçosa, Av. P.H. Rolfs, S/N, DBG, ECS333, Campus Universitário, Viçosa, 36570-900, Brazil.
Morais-Santos, Monica
  • Department of Animal Biology, Federal University of Viçosa, Viçosa, Brazil.
Vergara, Jose Carlos Montes
  • Department of Animal Science, Universidad de Córdoba, Monteria, Colombia.
Machado-Neves, Mariana
  • Postgraduate Program in Veterinary Medicine, Department of Veterinary, Federal University of Viçosa, Viçosa, Brazil. mariana.mneves@ufv.br.
  • Laboratory of Structural Biology, Department of General Biology, Federal University of Viçosa, Av. P.H. Rolfs, S/N, DBG, ECS333, Campus Universitário, Viçosa, 36570-900, Brazil. mariana.mneves@ufv.br.

MeSH Terms

  • Animals
  • Male
  • Epididymis / anatomy & histology
  • Swine / anatomy & histology
  • Cattle / anatomy & histology
  • Rats / anatomy & histology
  • Horses / anatomy & histology
  • Species Specificity
  • Testis / anatomy & histology

Grant Funding

  • 001 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
  • RED-00079-22; APQ-00361-23; BPD-00843-22 / Fundação de Amparo à Pesquisa do Estado de Minas Gerais
  • 420077/2018-9; 313524/2021-1 / Conselho Nacional de Desenvolvimento Científico e Tecnológico

Conflict of Interest Statement

Declarations. Ethics approval and consent to participate: All experimental procedures were reviewed and approved by the Ethics Committee for the Use of Experimental Animals at UFV (CEUA; protocols 1064/2021 and 1076/2021). Consent for publication: Not applicable. Competing interests: The authors declare no competing interests.

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