Ultrastructure of matriceal changes in chronic phase of Masugi nephritis by quick-freezing and deep-etching method

Abstract

The three-dimensional ultrastructure of glomerular sclerosis in the chronic phase of Masugi nephritis was investigated using a quick-freezing and deep-etching method. Newly formed mesangial matrix, which was increased in the axial portions, was composed of fine fibrillar networks similar to those in the lamina densa of the basement membrane. These fibrils were 10-20 nm in diameter and directly attached to the cell membranes of mesangial cells, endothelial cells and podocytes by connecting fibrils. Moreover, thicker fibrils with diameters of 20-30 nm were present in the networks and were connected with cross-bridges. A newly formed matrix of fine fibrillar networks was also seen in the areas of mesangial interposition in the glomerular capillary wall. The border between the matrix and lamina densa was unclear. The fibrils organizing the networks of lamina densa of the glomerular loop were thickened, with some decoration. Connecting fibrils were disrupted in the areas of endothelial detachment. It is suggested that prolonged tissue injury with endothelial detachment might induce mesangial sclerosis composed of fine fibrillar networks. The increase in density of the networks seemingly interfere with the contractile function of mesangial cells, which is followed by alteration of mesangial flow.

Three-Dimensional Study of Glomerular Lesions in Murine Chronic Graft-versus-Host Reaction by the Quick-Freezing and Deep-Etching Method

“…In serum sickness nephritis, immune deposits were seen in the mesangial matrix, and meshworks were disrupted around them [12]. In Masugi's nephritis, it is known that the sclerosis consisted of condensed fine fibril lar meshwork structures more thickened fibrils (type I col- lagen) were connected with [11], It is reported that mesangial deposits may induce the secretion of IL-1 or cytokines and as a result glomerular sclerosis develops [14,15]. In the present model, mesangial matrices contained increased thick fibrils resembling collagen fibers, which might be related to the development of the sclerosis.…”

“…Moreover, focal mesangiolytic changes were seen at stages later than the 7th week. These morphological findings sug gested that the deposition of the immune complex might appear during an early period of the illness in comparison with the data of ELIZA [7], Recently, three-dimensional ultrastructures of normal glomeruli have been reported by the quick-freezing and deep-etching method [8,9], Moreover, there have been other ultrastructural studies about pathological changes, such as Masugi's nephritis and serum sickness nephritis [10][11][12]. In the chronic phase of Masugi's nephritis, newly formed mesangial matrices were composed of fine fibrillar meshworks and related to the mesangial sclerosis [11].…”

Three-Dimensional Ultrastructure of Human Glomerular Basement Membrane by a Quick-Freezing and Deep-Etching Method

“…Recent ly, the QF-DE method was applied to clarify the threedimensional ultrastructure of the GBM in normal rats [8] or some models of renal diseases in animals [9][10][11][12][13][14], How ever, the renal tissues for our replica preparations have needed large sizes, 2x2x4 mm to obtain lots of infor mation about glomerular structures. So the QF-DE meth od has not yet been applied to biopsied materials from human kidneys.…”

Immune Deposits in the Glomerular Extracellular Matrix Detected by the Quick-Freezing and Deep-Etching Method

“…The QF-DE method is a new electron microscopy tech nique that permits the three-dimensional visualization of ultrastructural details, especially those of the cell mem brane, and cytoskeletal and extracellular filamentous com ponents [12][13][14][15][16][26][27][28][29][30][31][32]. After rapid freezing and freeze-frac turing, the surface layer of a biological structure is exposed by deep-etching for the sublimation of ice, followed by rotary shadowing with platinum metal and carbon.…”

“…We have already performed sev eral studies on glomeruli using this method [12][13][14][15][16]. In the present study, the deposition of immune complexes and the extracellular matrix in rats with serum sickness nephritis were examined by using the QF-DE method and immuno histochemical staining of the deposits on replica mem branes.…”