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Incorporation of 3H-proline in the mouse kidney was studied by electron microscopic radioautography in a pulse-chase mode to establish the role of visceral epithelial, endothelial, and mesangial elements in the synthesis and turnover of glomerular basement membrane. Visceral epithelial and endothelial cells were found to play a significant role in the formation of glomerular basement membrane components, and turnover time for one of the components was found to be under 2 h. The synthesis of second component is slow and may take 8–24 h. The mesangial cells appear to play a significant role in the reabsorption of the component with a faster turnover rate.

Large intramitochondrial dense bodies of irregular shape and without limiting membranes were observed during the ethionine intoxication in rats. Sodium or potassium deficiencies superimposed upon the ethionine injury had no effect on the occurrence of these bodies, while hypoxic conditions caused a considerable increase. The dense bodies are considered to be responses to severe though non-specific cellular injuries. They appear to be derived, at least in part, from altered groups of cristae.

Electron microscopy was performed on biopsy material from 179 patients with a variety of renal diseases. Electron microscopy established or significantly contributed to the diagnosis in 11 patients (6%) for whom light microscopic findings were normal or not definitive. It was most helpful in distinguishing renal vein thrombosis from other causes of membranous glomerulonephritis and in diagnosing tubular necrosis as the cause of acute renal failure and early diabetic glomerulosclerosis as the cause of asymptomatic proteinuria. It did not contribute to the diagnosis or management of the other renal diseases studied. Electron microscopy need not be performed as a routine procedure but it should be available for the occasional occurrence that otherwise defies diagnosis.

The advances made in recent years in the medical and surgical management of tuberculosis have prompted a renewed interest in a form of tuberculosis which mainly affects the aorta. The disease, while uncommon, is important because it will lead to serious consequences if untreated. Generally, the aorta becomes involved by direct extension from periaortic foci such as tuberculous lymph nodes or psoas abscesses and this finally results in aneurysm formation or perforation or both. Fatal complications can be prevented by early recognition and prompt surgical intervention. These principles are illustrated by the case histories of a woman aged 25 and 2 men aged 59 and 60 years.

Excerpt Three patients with renal glycosuria and proteinuria were evaluated by tubular function tests and kidney biopsy, using light and electron microscopy (EM). A schoolgirl aged 6 and two men ag...