Effect of Irradiation on Secretory Cells of Submandibular Gland of Adult Male Albino Rat. Histological and Immunohistochemical Study

Introduction: The submandibular glands are commonly included in the radiotherapy field for the treatment of head and neck malignancies. Many clinical problems are produced but their mechanisms are still not understood. Aim of the Work: Was to study the effect of irradiation on secretory cells and aquaporin 5 (AQP5) distribution in submandibular gland as a trial to understand the mechanism of gland dysfunction. Materials and Methods: 15 adult male albino rats were used and were divided into two groups, group A (control group) contained five rats and group B (irradiated group) contained ten rats. Each rat in group B was irradiated with single dose of 15Gy delivered by the X-ray unit. One week after irradiation submandibular glands were dissected and were processed for histological and immunohistochemical (aquaporin 5) examination. Results: LM study exhibited that irradiation led to cytoplasmic vacuolization especially in serous acini with widening of spaces in-between the acini in the submandibular glands. EM study showed irregular nuclei with chromatin condensation, dilatation of RER and cytoplasmic vacuolization. As regards the secretory granules, serous acini showed degranulation while the granules of mucous acini exhibited amorphous-like electron dense materials. Aquaporin 5 (AQP5) in the control group was localized in apical membrane of serous acini while absent in mucous one. After irradiation the serous acini of submandibular glands exhibited marked decrease in AQP5. Conclusion: Irradiation induced morphological disruption in secretory cells of submandibular gland and marked decrease in AQP5, both would responsible for gland dysfunction.