Histochemistry and ultrastructure of the cell surfaces of the guinea pig kidney with quantitative data on carbohydrate components of glycosaminoglycans of kidney

Summary

This report deals with a histochemical, electron microscopic and chemical study of carbohydrates of the guinea pig kidney. Histochemical reactions were positive for glycoproteic components in the lumenal surface of the proximal convoluted tubules as well as in the basal aspects of tubular cells. Mucosubstances containing carboxyl and sulphate groups and sialic acid were present at the cell surfaces of the Bowman's capsule, proximal and distal convoluted tubules, loop of Henle and, in greater concentrations, at the cell surfaces of the collecting tubules and papillary epithelium. Data seemed to indicate that glycosaminoglycans were present at the cell surfaces of the collecting tubules.

By electron microscopy, the alcian blue stained a dense coat of granular appearance at the lumenal surface of the loop of Henle, measuring up to 100 nm in thickness. Ruthenium red stained the glycocalyx of the collecting tubules which measured up to 60 nm in thickness. The glycocalyx of the collecting tubules was made up of thin filaments and a dense component of about 10 nm thick which merged with the outer leaflet of lumenal plasma membrane, which thus appeared asymmetric. With Alcian blue, the glycocalyx of the collecting tubules, which measured 600 to 1500 nm in thickness, was made up of a meshwork of filaments containing globular or irregular structures measuring 50 to 150 nm in diameter. Chemical assays of kidney homogenates revealed carbohydrate components and sulphate of glycosaminoglycans.