抄録
The site of dephosphorylation of S-benzoylthiamine O-monophosphate (BTMP) was detected cytochemically by electron microscopy. At pH 9.0,incubation of intestinal tissue of mouse with BTMP at 5℃ for 5 minutes revealed that the phosphatase reaction is predominant at the outer surface of unit-membrane structure of the microvilli. The absorption mechanism of BTMP was further demonstrated by electronmicroscopic autoradiography. Using hydrogen platinum chloride as a precipitating reagent for thiamine compounds in tissue, it was shown that electron-dense precipitates of the Pt-salts of thiamine and S-benzoylthiamine and the developed silver grains appear only inside the membrane of microvilli, on the core of microvilli, in cytoplasm and mitochondria, on the membrane of Golgi apparatus and rough surfaced endoplasmic reticulum, in nucleus, basement membrane, endothelial cell of blood capillary and red blood cells, indicating the main pathway of the intestinal absorption of BTMP. The fact that the developed silver grains appear only inside the membrane of microvilli agrees with the fact that dephosphorylation of BTMP occurs only outside the membrane, since BTMP does not form insoluble precipitates with hydrogen platinum chloride.
