A computer-aided 3-D geometry of acute and chronic zonal necrosis: three-D tangent counting applied in an attempt to re-examine the structure of the human liver.

In an attempt to examine the feasibility of the acinar concept in the liver of humans, the spatial distribution of zonal necrosis and its relation with the blood vessels were studied in terms of 3-D tissue microstructure. The material was five autopsy livers, two from patients of acute cresol intoxication and three with long-standing heart failure. Examined were: 1) whether the surviving areas (zones 1, 2) in acute zonal necrosis have surfaces convex toward the necrotic zone 3 as illustrated in the acinar schema, and 2) whether the necrosis extends as slender "s eeves" so as to reach the portal tracts and create portal-central (P-C) bridging, leaving zones 1 and 2 as a spheroid parenchymal clump. These were examined on serial histological sections of the livers, which were subjected to 3-D reconstruction with the aid of a computer system. The geometric properties of the interfaces between the surviving and necrotic areas were analyzed by 3-D tangent counting technique of DeHoff modified for 3-D application. It was shown by reconstruction that necrosis was uniformly distributed around the hepatic venules. In acute cases, tangent counting showed that the surfaces of the surviving areas were mainly concave toward necrosis. In contrast, in chronic cases, the surfaces became mainly convex as a result of parenchymal regeneration. At no place, in acute or chronic cases, was necrosis shown to reach the portal tracts, and because of this, neither acini nor their agglomerates revealed themselves as a separate unit. All these findings contradict what one expects would be, so long as based on the assumption of the acinar model.