Histological Assessment of Intestinal Mucosal Barrier Integrity Following Acute Heat Stress in a Porcine Model

International Journal of Anatomy and Physiology | Vol. 15, No. 10, October 2026 | pp. 91–99

DOI: 10.46882/2026/IJAP/001011

Research Article

Title: Histological Assessment of Intestinal Mucosal Barrier Integrity Following Acute Heat Stress in a Porcine Model

Names of Authors: Y. J. Feng¹, A. R. O’Connor², J. M. Santos³*

Authors’ Affiliations:
¹ State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, China.
² Department of Veterinary Physiology, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA.
³ Department of Morphology, University of Campinas, Campinas, São Paulo, Brazil.

Abstract:
Acute hyperthermia disrupts intestinal homeostasis, altering the morphological structures of the mucosal barrier and increasing susceptibility to systemic endotoxemia. This study examined the time-course effects of acute heat stress on the histological structure of the jejunum and ileum using a porcine model. Sixteen crossbred barrows were exposed to either thermoneutral conditions (21°C, 45% humidity) or acute heat stress (37°C, 60% humidity) for durations of 2, 4, or 6 hours (n = 4 per group). Intestinal segments were processed for light microscopy, scanning electron microscopy, and immunohistochemical localization of the tight junction protein zonula occludens-1 (ZO-1). Heat stress induced severe time-dependent morphological injuries. Villus height in the jejunum decreased significantly after 4 hours of exposure (285 ± 18 μm vs. 410 ± 25 μm in thermoneutral controls; p < 0.01), accompanied by subepithelial space formation at the villus tips (Gruenhagen’s spaces). Crypt depth increased, resulting in a significantly lower villus-to-crypt ratio (1.25 ± 0.11 vs. 2.10 ± 0.15; p < 0.05) after 6 hours. Scanning electron microscopy revealed focal epithelial desquamation and microvilli remodeling. Immunohistochemistry showed a progressive loss and discontinuous distribution of ZO-1 along the apical membrane of enterocytes. These results demonstrate that acute hyperthermic stress rapidly damages the mucosal architecture, providing structural context for the intestinal hyperpermeability observed during severe heat stroke.

Keywords: Mucosal barrier, Jejunum, Ileum, Heat stress, Zonula occludens-1, Histopathology.

Manuscript Timeline: Received: June 28, 2026; Revised: August 22, 2026; Accepted: September 12, 2026; Published: October 11, 2026.

Citation: Feng YJ, O’Connor AR, Santos JM. Histological Assessment of Intestinal Mucosal Barrier Integrity Following Acute Heat Stress in a Porcine Model. International Journal of Anatomy and Physiology. 2026; 15(10): 91–99. doi:10.46882/2026/IJAP/001011

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