Portal de Periódicos da CAPES

The intestinal brush border

1971; BMJ; Volume: 12; Issue: 8 Linguagem: Inglês

10.1136/gut.12.8.668

1468-3288

R. Holmes,

Dietary Effects on Health

Progress reportThe intestinal brush borderThe appearance of the striated border of intestinal epithelial cells under the light microscope was described many years ago1, and the first demonstration that this border consisted of fine projections or microvilli was made by Granger and Baker in 19492 using the electron microscope.Since that time the intestines of many species including man have been shown to possess brush (microvillous) borders3, and there are approximately 1,700 microvilli on each epithelial cell4.A single microvillus measures about 1 micron in length and 0.1 micron in diameter, and the total brush borders of the small intestine have been estimated to increase the surface of the absorptive cells thirty-to forty-fold4.In 1961, Miller and Crane5 separated intact brush bor- ders from the epithelial cells of hamster small intestine.Over the last 10 years the microvilli of intestinal epithelial cells have been investigated intensively for digestive, absorptive and binding functions, and they have been the sub- jects of several reviews6 7,899,10,11 and one symposium12.In this report no attempt will be made to review the subject exhaustively but rather to highlight the important functional aspects and also to discuss some more recent developments. Historical and Technical AspectsAs early as 1880, Brown and Heron13 showed that enzymes hydrolysing disaccharides were present mainly in the intestinal mucosa rather than in the intestinal juice and this finding has been repeatedly confirmed14'15'1f"7'18.Nevertheless, for many years it was generally considered19 20 that the terminal phase of carbohydrate and protein digestion took place by the action of enzymes secreted into the lumen in the intestinal juice or succus entericus.However, the localization of certain enzymes to the brush border by histo- gatorS27 28,29,30 and confirmed by different methods24'31 and have provided impressive evidence against the idea that succus entericus played a major role in terminal digestion in the small intestine.