Quantitative Histomorphometry of Thyroid Gland Remodeling in Rats Following Chronic Exposure to Nitrate-Contaminated Drinking Water

International Journal of Anatomy and Physiology | Vol. 15, No. 11, November 2026 | pp. 226–234

DOI: 10.46882/2026/IJAP/001026

Research Article

Title: Quantitative Histomorphometry of Thyroid Gland Remodeling in Rats Following Chronic Exposure to Nitrate-Contaminated Drinking Water

Names of Authors: I. M. Petrović¹, O. S. Adeyemi²*

Authors’ Affiliations:
¹ Institute of Histology and Embryology, Faculty of Medicine, University of Belgrade, Belgrade, Serbia.
² Department of Anatomical Sciences, Faculty of Basic Medical Sciences, University of Ilorin, Ilorin, Nigeria.

Abstract:
Nitrate compounds are ubiquitous environmental contaminants found in agricultural runoff that can interfere with thyroid iodine uptake, disrupting endocrine homeostasis and glandular tissue architecture. This study investigated the structural consequences of chronic ingestion of sodium nitrate on the thyroid parenchyma of adult Wistar rats using quantitative histomorphometry. Thirty male Wistar rats were divided into three groups of ten: Control (distilled water), Low-Exposure Nitrate (50 mg/L), and High-Exposure Nitrate (500 mg/L), administered via drinking water for 16 consecutive weeks. Thyroid glands were harvested, fixed, sectioned, and stained with Hematoxylin and Eosin (H&E). Histomorphometric evaluation revealed significant tissue remodeling in the treated cohorts. The mean follicular epithelial height increased significantly in the high-exposure group (14.2 ± 1.8 μm vs. 6.4 ± 0.7 μm in controls; p < 0.01), representing a shift from cuboidal to columnar epithelium due to compensatory hyperstimulation. Concurrently, the mean follicular diameter decreased significantly (45.2 ± 4.1 μm vs. 78.5 ± 6.2 μm in controls; p < 0.01), indicating accelerated colloid depletion. Interstitial vascular volume fraction expanded significantly from 3.8% ± 0.5% in controls to 9.2% ± 1.2% in the high-dose cohort (p < 0.05), demonstrating regional hypervascularization. These objective tissue alterations show that chronic exposure to environmental nitrates induces severe architectural stress and follicular remodeling within the thyroid gland, highlighting potential risks for environmental goitrogenesis.

Keywords: Thyroid gland, Nitrate, Histomorphometry, Follicular epithelium, Endocrine disruptor.

Manuscript Timeline: Received: August 22, 2026; Revised: October 10, 2026; Accepted: November 01, 2026; Published: November 22, 2026.

Citation: Petrović IM, Adeyemi OS. Quantitative Histomorphometry of Thyroid Gland Remodeling in Rats Following Chronic Exposure to Nitrate-Contaminated Drinking Water. International Journal of Anatomy and Physiology. 2026; 15(11): 226–234. doi:10.46882/2026/IJAP/001026

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