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What is "Tram track" appearance is seen in- and explain in detail?
By light microscopy, type I MPGN and many cases of dense deposit disease are similar. The glomeruli are large, with an accentuated lobular appearance, and show proliferation of mesangial and endothelial cells as well as infiltrating leukocytes. The GBM is thickened, and the glomerular capillary wall often shows a double contour, or "tram track," appearance, especially evident with the use of silver or periodic acid-Schiff (PAS) stains. This "splitting" of the GBM is due to the extension of processes of mesangial and inflammatory cells into the peripheral capillary loops and deposition of the mesangial matrix. Ref: Robbins basic pathology 9th edition page527