[Reconstruction of glomerular tufts--observation of mesangiolysis induced by anti-thymocyte serum]

The reconstruction process of the glomerular capillary structure following mesangiolysis induced in rats by anti-thymocyte serum (ATS) was investigated for three months. Cystic ballooning change of the glomerular tufts was remarkable four days after the administration of ATS, which was followed by inflammatory cell infiltration, and hypercellularity in mesangial area was observed one week later. Glomerular tufts were gradually reconstructed thereafter, leaving focal and segmental sclerotic or adhesive lesions. In the periphery of the ballooning area, a large vascular lumen was subdivided into smaller capillary lumina by endothelial and mesangial bridging, which resembled to the process in the fetal glomerulogenesis. The endothelial cells in mesangiolysis connected one another by junctional complexes and formed new capillary structure. The mesangial cells got in touch with the endothelial cells by mesangial bridging. In the proliferative lesion, endothelium-like cells could be recognized by immunostaining and had fenestrae with diaphragmatoid structure without mature basement membrane in the initial stage on electron microscopic observation. Interstitial-typed collagen fibers were found in the proliferative lesion, and they still existed in the focal segmental sclerotic lesion in the late stage of the experiment. The glomerular basement membrane (GBM) was seen to be reformed by fusing the original GBM with the newly synthesized one covering subendothelial space, where mesangial cells were interposed. Endothelial cells, endothelial-mesangial interaction and extracellular matrix formation seemed to play an important role in reconstruction of the glomerular tufts after mesangiolysis induced by ATS.