Thickening of the glycocalyx during methotrexate induced small intestinal mucosal atrophy in the rat.

In this study, the morphology of the glycocalyx of small intestinal enterocytes in the rat was investigated after the induction of mucosal atrophy by methotrexate (MTX) in 18 Wistar rats. On the 2nd, 4th and 6th day after the intraperitoneal administration of MTX, a group of 6 rats was sacrificed and tissue specimens taken at the level of the Treitz' ligament were post fixed in a mixture of 2.0% watery osmiumtetroxide and 1.5% potassium-ferrocyanide to enhance visibility of glycoconjugates and processed for electron microscopy. In the control rats, the glycocalyx was hardly visible on the villous enterocytes, but rather conspicuous on the enterocytes in the crypts. On the second day after injection of MTX, the glycocalyx of the villous enterocytes was more pronounced but on the crypt enterocytes it resembled that of control animals. On the 4th day after MTX administration, a striking reduction and shortening of microvilli of villous enterocytes was seen, together with very pronounced glycocalyces, while crypt cells possessed well developed cell coats. On the 6th day after the injection of MTX, the glycocalyx of both villous and crypt cells appeared almost normal again.