Kubo. Vascular endothelial growth factor in patients with high-altitude pulmonary edema.

The glomerular basement membrane of rat kidneys were three-dimensionally observed by quick-freeze and deep-etch replica methods at high resolution. The middle layer (lamina densa) was composed of 6 to 10 nm fibrils which formed a meshwork structure. The space between the fibrils had polygonal shape. The average long dimension of the space between fibrils was 17 nm and the short one was 13 nm. At the outer layer (lamina rara externa), fibrils connected podocytes perpendicularly with the meshwork of the middle layer. At the inner layer (lamina rara interna), similar perpendicular fibrils also connected endothelial cells with the meshwork of the middle layer. This is the first report to visualize the three-dimensional meshwork structure of the middle layer (the lamina densa) in situ. The function of anchoring podocytes to the lamina densa was suggested in the perpendicularly arranged fibrils of the outer layer. The quick-freeze and deep-etch method is useful in analyzing filamentous ultrastructure in glomeruli, and will be applied to clarifying pathological ultrastructure in kidney diseases.

We observed hepatocyte cytoskeletons in phalloidin-treated rats by the quick-freezing and deep-etching method in three dimensions and compared them with the ultrastructural findings on conventional ultrathin sections. The numbers of microvilli in dilated bile canaliculi were decreased in the rats treated with phalloidin for 1 wk. In hepatocytes the cytoplasm around bile canaliculi could be divided into three layers, increased microfilament layer, cell organelle layer of secretory system and increased smooth surface endoplasmic reticulum layer. In the rats treated with phalloidin for 4 wk, microfilaments were extended into the cytoplasm near the nucleus in addition to the increased number of large lysosomes and microtubules. In both groups, three-dimensional structures of microfilaments could be visualized around bile canaliculi and along cell borders by the quick-freezing and deep-etching method. The branching microfilaments with the diameters of 7 to 10 nm were directly attached to other filaments, cell organelles or cytoplasmic sides of cell membranes. Moreover, bundled intermediate filaments were increased around peribiliary microfilaments associated with long-term cholestasis. It is suggested that excessive accumulation of peribiliary microfilaments disturb the secretion of bile components into bile canaliculi. The cytoskeletal reorganizations of intermediate filaments seem to alter the arrangements of various cell organelles.

The three-dimensional ultrastructure of the glomerulus in serum sickness nephritis has been investigated by the quick-freezing and deep-etching method. Compact granular immune deposits were localized in filamentous networks in the lamina densa and mesangial matrices. These constitutional fibrils with diameters of 8-15 nm, were directly attached to the immune deposits. The filamentous networks became markedly loosened around the deposits. In podocytes, reticular microfilaments with positive decoration by myosin subfragment 1 (S1) were increased in flattened foot processes and directly attached to the cell membranes. Fine filaments with diameters of 4-7 nm were undecorated by S1 and connected with actin filaments as cross-bridges. Intermediate filaments were also increased in the cell bodies and primary processes of podocytes. Connecting fibrils in lamina rara externa were partially disrupted. The immune deposits were primarily detected in the networks of lamina densa and actually destroyed the size barrier composed of filamentous networks. Moreover, the mesangial deposits also disorganized mesangial networks to probably alter mesangial flow through the matrices. Increased actin filaments in foot processes seemingly reinforced the cell membranes and the connecting fibrils in lamina rara externa, which prevented the initial detachment of podocytes from the basement membrane.

No abstract