Effects of oral administration of formaldehyde on albino rat stomach: light and scanning electron microscopic study

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Formaldehyde is one of the food additives used to preserve foods.

Aim of the study

To evaluate the histological changes produced by oral administration of formaldehyde on albino rat stomach.

Materials and methods

Twenty adult male albino rats were divided into two groups: a control group (I) and an experimental group (II), which received commercial formaldehyde solution orally (80 mg/kg) daily for 4 weeks. Fore-stomach sections were stained by H&E. Glandular-stomach sections were stained by H&E, alcian blue PAS, and Feulgen reactions for light microscopic examination. Specimens from both stomach portions were processed for scanning electron microscopic examination. Thickness of mucosa, area % of alcian blue PAS reaction, and optical density of the Feulgen reaction were measured using an image analyzer. Data were subjected to statistical analysis.


After the intake of oral formaldehyde, there was a significant increase in the thickness of the stomach lining epithelium. Fore-stomach sections revealed an irregular surface, excessive keratin scale, and basal cell hyperplasia with regional loss of papillation as well as inflammatory cellular infiltrations. Glandular-stomach sections exhibited scattered surface erosion and necrotic debris. Inflammatory cellular infiltrations and dilated blood vessels associated with edematous spaces were observed. The gastric gland cells showed cytoplasmic vacuolation, cystic dilatation, and apparent hyperplasia. There was a significant decrease in alcian blue PAS and Feulgen reactions.


The intake of oral formaldehyde has deleterious gastric effects in the form of irritating, regenerative effects as well as DNA damage that may be precancerous.

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