Ultrastructure of Brunner’s glands in the horse.

This research article explores the unique features of Brunner’s glands, a type of duodenal submucosal gland, in horses by examining them at the ultrastructural level. A significant finding is that these glands comprise both mucous and serous tubuloacinar glands, a characteristic relatively rare among mammals.

Understanding Brunner’s Glands

• The study focuses on the Brunner’s glands located in the duodenum of horses. Duodenum is the first section of the small intestine immediately beyond the stomach, leading to the jejunum.
• Brunner’s glands are specific types of submucosal glands found in the duodenum. Interestingly, in horses, these glands comprise of both mucous and serous tubuloacinar glands.
• Typically, Brunner’s glands play an essential role in secreting mucus, which assists in the activity of digestion and protection of intestinal walls from acidic chyme. Such dual glandular composition is uncommon amongst mammals in general, signaling towards a specific adaptive feature in horses.

Ultrastructural Differences

• On the ultrastructural level, significant differences were observed between the serous and mucous cell types, particularly concerning their secretory granules and rough endoplasmic reticula. Despite these differences, these cells are believed to correspond closely to similar cell formations in the digestive systems of other mammals.
• Besides the main two types of cells, a smaller, distinctive population of goblet-cell like mucous cells and endocrine-like cells were also found among the Brunner’s glands in horses. Goblet cells are specialized cells that produce mucus, while endocrine cells secrete hormones directly into the bloodstream.

Function of Brunner’s Glands in Horses

• The research illustrates that both the serous and mucous cells seem to empty their secretions into common ducts entering the base of the duodenal crypts.
• Fusing this cytological data with other physiological data, the research suggests that Brunner’s glands in horses serve dual functions: They act as protective barriers by producing mucus for the proximal duodenum and release digestive enzymes like lipase or other yet unidentified materials. The glands’ mucosal protection mechanism is crucial as it shields the intestinal walls from the potentially damaging effects of digestive enzymes and acidic chyme.