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Study Maps the Eye Glands of Natal Red Duikers and Kirk’s Dik-Diks

Female Natal red duiker eating fruit in Umlalazi Nature Reserve, South Africa
Research · Anatomy & morphology

A 2026 anatomical study provides a detailed description of the gland complex that protects the eye surface in Natal red duikers (Cephalophorus natalensis) and compares it with Kirk’s dik-diks (Madoqua kirkii). These structures had been poorly documented in both small African antelopes.

The study examined post-mortem material from five young Natal red duikers and four young Kirk’s dik-diks from Wrocław Zoo in Poland. The animals had died independently of the research, and the researchers reported no visible abnormalities in the eyes or surrounding tissues when the samples were collected.

On both sides of the head, the team examined three glands involved in maintaining and protecting the ocular surface: the Harderian gland, the lacrimal gland and the superficial gland of the third eyelid. The tissues were studied macroscopically and under the microscope, and a series of histochemical stains was used to identify different components of the glandular secretions.

The three glands occupied distinct parts of the orbit

In both species, the three glands occupied distinct parts of the orbit. The Harderian gland was positioned on the inner and lower side of the eye, the lacrimal gland on the upper outer side, and the superficial gland of the third eyelid close to the third eyelid. Microscopically, the glands were built from branching secretory units with tubular and rounded acinar portions, although some were dominated by the rounded acini. The examined glands also differed in capsule thickness, internal septa, lobular organisation and the appearance of the secretory cells.

The histochemical analyses showed a mixture of neutral glycoconjugates and acidic mucosubstances in the secretions, although their relative occurrence varied between glands and between the two groups of animals. Plasma cells and lymphocytes were also present within the glandular tissue, reflecting the immune functions associated with the ocular surface.

The small sample limits species-level conclusions

The authors emphasise that this was a preliminary descriptive study with only five red duikers and four dik-diks. They did not statistically test whether the observed differences between the two small groups were larger than might be expected from individual variation. The observed differences should therefore not be treated as definitive species-level characteristics. Instead, the results establish reference material for comparative anatomy and for veterinary examination of orbital tissues in zoo and wildlife medicine.

Sources and image credit

  1. Klećkowska-Nawrot, J., Chrószcz, A., Aktaş, A., Barszcz, K., Paszta, W., Goździewska-Harłajczuk, K., & Poradowski, D. (2026). Preliminary Anatomical, Histological, and Histochemical Study of the Orbital Gland Complex in Kirk’s Dik-Dik (Madoqua kirkii) and Red Forest Duiker (Cephalophorus natalensis). Veterinary Sciences, 13(8), 752. https://doi.org/10.3390/vetsci13080752Primary peer-reviewed open-access study, published 29 July 2026

Image: Bernard DUPONT — female Natal red duiker eating fruit in Umlalazi Nature Reserve, South Africa. Source: Wikimedia Commons. Representative image for this story; not presented as an animal or scene from the reported study or event. · CC BY-SA 2.0 · Source

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Anatomy & morphology

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