Brush cells in the human duodenojejunal junction: an ultrastructural study

Brush cells are epithelial structures found in multiple mammalian species. In humans, these cells appear in the respiratory and gastrointestinal systems, including the stomach and gallbladder. Their function remains unclear, and most ultrastructural data derive from rodent models. Prior research has not fully characterized human brush cells in the small intestine. This gap motivated a detailed ultrastructural analysis of human brush cells. No prior work had resolved the specific morphology of these cells in the human duodenojejunal junction. The study aimed to clarify the structure of human brush cells in this region. Understanding their ultrastructure could inform their functional roles in human physiology. This investigation builds on existing morphological knowledge to explore new aspects of brush cell biology.

The aim of this study was to describe the ultrastructural features of brush cells in the human small intestine. Researchers focused on the duodenojejunal junction, a region where brush cells have not been extensively studied. The specific problem addressed was the lack of detailed morphological data on human brush cells in this area. By analyzing biopsy samples, the study sought to clarify the cellular architecture of these cells. The motivation was to extend knowledge beyond rodent models to human tissue. The goal was to identify structural features that might suggest functional roles. The study also aimed to detect any novel associations with nerve fibers. This work contributes to understanding the potential sensory or signaling functions of brush cells.

Researchers examined human small intestine biopsies using transmission electron microscopy. A total of over 300 biopsies were analyzed for brush cell presence. Six brush cells were identified in five biopsies from patients with gastrointestinal disorders. The cells were located either on the surface epithelium or within crypts. Apical microvilli were measured and compared to those of enterocytes. Filamentous structures and cytoskeletal components were analyzed. The presence of caveolae and dense core granules was noted. Nerve fiber associations were observed in one of the brush cells examined.

Five brush cells were found on the surface epithelium, and one in a crypt. The apical microvilli of brush cells were longer and thicker than those of enterocytes. Filamentous cores extended into the cell body without forming a terminal web. Abundant caveolae were observed on the apical surface of brush cells. Filaments included both microfilaments and intermediate filaments. Cytoplasmic projections containing filaments were noted on the basolateral surface. A single brush cell showed axons with vesicles and dense core granules in close contact. The crypt brush cell appeared less mature than surface cells.

Human small intestine brush cells share ultrastructural features with those in other mammals. These cells are polarized and well-differentiated with a distinctive cytoskeleton. The presence of microvilli and filamentous cores supports this conclusion. The absence of a terminal web distinguishes brush cells from enterocytes. The observation of caveolae and dense core granules was consistent with prior findings. The study confirmed the presence of nerve fiber associations in one brush cell. This finding supports the hypothesis that brush cells may have a receptor function. The results suggest a potential role in sensory signaling in the human gut.