Basal-granulated cells in human Brunner's glands

Basal-granulated cells (BGC) in the human duodenal bulb were observed by light and electron microscopy, and both the cell types and their population densities in the duodenal crypts and in the Brunner's glands were compared. The number of the BGC in the Brunner's glands was much smaller than in the crypts. On the basis of their ultrastructural features, nine types of BGC, i.e. an EC cell, N cell, D cell, D1 cell, S cell, I cell, G cell, L cell and P cell were identified in the human duodenal bulb. In the duodenal crypts, as is generally recognized, EC cells were most numerous, making up 40% of the total BGC. N cells and D cells were around 10% of the total, and S cells, I cells and L cells were less than 10%, respectively. By contrast, in Brunner's glands, D cells and small granule-containing cells such as S cells, I cells and D1 cells were predominant, accounting for about 80% of the total BGC. EC cells and N cells were about 10% or less, respectively. These results indicate that the Brunner's glands are definitely different from the ordinary intestinal mucosa in regard to their BGC population, and are considered to have endocrine functions mainly performed by D1 cells, S cells and I cells.