Histomorphometric and Microscopic Assessment of Gastric Mucosa in Guinea pig and White Rat Models

The understanding of rodent gastrointestinal morphology is important for several medical applications, including experimental surgical procedures, the diagnosis of gastric disorders, and providing information about diet adaptation and gut physiology. Therefore, the present study aimed to investigate the anatomical, morphometric, and microscopic characteristics of the gastric mucosa in adult guinea pigs and white rats. Stomachs from five healthy adult guinea pigs (Cavia porcellus) and five white rats (Rattus norvegicus) were collected and preserved in 10% formalin. The samples were later processed, sectioned, and stained with Harris Hematoxylin and Eosin. Microscopic measurements were made for the depth of gastric pits, diameter of gastric glands, and the thickness of the gastric mucosa, tunica submucosa, tunica muscularis, and tunica serosa. The number of parietal and chief cells was counted in the fundic and pyloric regions of both animals. The rat stomach was crescent-shaped, with distinct non-glandular and glandular regions. While the stomach of guinea pig was pear-shaped, totally glandular. The mucosal microstructure exhibited variations in thickness and morphology. The rat's non-glandular mucosa had keratinized squamous epithelium, while the guinea pig lacked a non-glandular region. Histologically, gastric pits and glands differed in size, density, and cellular composition, with guinea pigs showing thicker muscular layers and larger, less dense glands, while rats had more parietal and chief cells in the fundic and pyloric regions. This study enhances the understanding of how dietary habits shape gastric anatomy and physiology. Future research could explore enzymatic activity, gut microbiota interactions, developmental anatomy, and the mechanisms underlying these adaptations.