Krause W J
Department of Pathology and Anatomical Sciences, School of Medicine, University of Missouri, Columbia, Missouri 65212, USA.
Prog Histochem Cytochem. 2000;35(4):259-367.
Brunner's glands are unique to mammalian species and in eutherians are confined primarily to the submucosa of the proximal duodenum. In the majority of species examined, they begin at the gastrointestinal junction and extend for variable distances distally in the wall of the proximal small intestine. Ducts of individual glands empty either directly into the intestinal lumen or unite with overlying intestinal glands (crypts of Lieberkühn) dependent on the species. Secretory units of Brunner's glands consist of epithelial tubules that show frequent distal branchings. The secretory units, with the exception of those found in rabbits and horses, consist primarily of a mucin producing cell type. However, other cell types normally associated with the overlying intestinal epithelium may be encountered scattered within the secretory units reflecting the developmental origin of these glands. Secretion from Brunner's glands contributes to a layer of mucus that forms a slippery, viscoelastic gel that lubricates the mucosal lining of the proximal intestinal tract. The unique capacity of this mucus layer to protect delicate underlying epithelial surfaces is due primarily to the gel-forming properties of its glycoprotein molecules. Mucin glycoproteins produced by Brunner's glands consist primarily but not exclusively of O-linked oligosaccharides attached to the central protein core of the glycoprotein molecule. Human Brunner's glands produce class III mucin glycoproteins and are thought to be the product of mucin gene MUC6 which is assigned to chromosome 11 (11p15-11p15.5 chromosome region). In addition to mucin glycoproteins and a limited amount of bicarbonate, numerous additional factors (epidermal growth factor, trefoil peptides, bactericidal factors, proteinase inhibitors, and surface-active lipids) have been identified within the secretory product of Brunner's glands. These factors, incorporated into the mucus layer, guard against the degradation of this protective barrier and underlying mucosa by gastric acid, pancreatic enzymes, and other surface active agents associated with this region. Yet other factors produced by Brunner's glands function to provide active and passive immunological defense mechanisms, promote cellular proliferation and differentiation, as well as contribute factors that elevate the pH of luminal contents of this region by promoting secretion of the intestinal mucosa, pancreatic secretion and gall bladder contraction. Additional insights concerning the role of Brunner's glands in the mammalian gastrointestinal tract as well as their possible evolution in this class of vertebrates have been gained from a basic understanding of their pathobiology.
布伦纳腺是哺乳动物特有的，在真兽类动物中主要局限于十二指肠近端的黏膜下层。在大多数被检查的物种中，它们始于胃肠交界处，并在近端小肠壁内向远端延伸不同的距离。单个腺体的导管要么直接排入肠腔，要么根据物种不同与覆盖其上的肠腺（利伯kühn隐窝）汇合。布伦纳腺的分泌单位由上皮小管组成，这些小管有频繁的远端分支。除了在兔子和马中发现的那些，分泌单位主要由产生粘蛋白的细胞类型组成。然而，通常与覆盖其上的肠上皮相关的其他细胞类型可能会分散在分泌单位中，这反映了这些腺体的发育起源。布伦纳腺的分泌物形成一层黏液，该黏液形成一种光滑的、具有黏弹性的凝胶，润滑近端肠道的黏膜。这种黏液层保护下面脆弱上皮表面的独特能力主要归因于其糖蛋白分子的凝胶形成特性。布伦纳腺产生的粘蛋白糖蛋白主要但并非完全由连接到糖蛋白分子中央蛋白核心的O - 连接寡糖组成。人类布伦纳腺产生III类粘蛋白糖蛋白，被认为是粘蛋白基因MUC6的产物，该基因定位于11号染色体（11p15 - 11p15.5染色体区域）。除了粘蛋白糖蛋白和少量碳酸氢盐外，在布伦纳腺的分泌产物中还鉴定出许多其他因子（表皮生长因子、三叶肽、杀菌因子、蛋白酶抑制剂和表面活性脂质）。这些因子融入黏液层，防止胃酸胰酶和与该区域相关的其他表面活性剂对这种保护屏障和下面的黏膜造成降解。布伦纳腺产生的其他因子还具有提供主动和被动免疫防御机制、促进细胞增殖和分化的功能，以及通过促进肠黏膜分泌、胰液分泌和胆囊收缩来提高该区域管腔内容物pH值的作用。通过对其病理生物学的基本了解，我们对布伦纳腺在哺乳动物胃肠道中的作用以及它们在这类脊椎动物中的可能进化有了更多的认识。
