THE USE OF A STEREOLOGICAL METHOD TO ESTIMATE THE VOLUME OF SCHISTOSOMA-MANSONI GRANULOMAS - THE EFFECT OF ZINC-DEFICIENCY

A quantitative, stereological method to assess the volume of Schistoso ma mansoni granulomas is presented and its use demonstrated in a study of zinc-deficient animals. Twenty-six mice were divided into two grou ps, and given zinc-deficient or control food. After 4 weeks, the mean weight gain and thymus size were lower in the mice on the zinc-deficie nt diet. Eight mice in each group were then each infected with 60 S. m ansoni cercariae and these mice were killed 12 weeks post-infection. T here were then more eggs in the livers of the zinc-deficient mice than in those of the infected controls (7400/female worm v. 3300/female wo rm; P = 0.02), probably because of impaired intestinal egg expulsion a nd impaired resorption of eggs in the deficient mice. The median propo rtion of each liver occupied by granulomas was 0.11 among the zinc-def icient mice and 0.09 among the pair-fed, control mice (P = 0.08), and the median liver volumes were 1400 and 1450 mu l (P = 0.49), respectiv ely. The computed median volume of all the granulomas in each liver wa s 160 mu l in zinc-deficient and 132 mu l in control mice (P = 0.32), while median granuloma volume per egg was 8.6 and 8.7 nl (P = 0.93), r espectively. In contrast to conventional methods, modern stereological methods can provide estimates of granuloma volume or granuloma volume fractions without any assumptions al rout the size, shape, orientatio n or distribution of the granulomas in the liver.