Some aspects of histochemical studies on the parasite and tissue reaction in bovine cysticercosis.

Histochemical studies on the cysticercus and surrounding tissue reaction were performed at various intervals after experimental infection. It was found that acid mucosubstances and proteins with SH- and SS-groups appeared first in the granulation tissue around the cysticercus (on about day 14 p.i.) and only later (on day 28 p.i.) in the tegument of the cysticercus where they were localized in the rim of microtriches. This envelope consisting of mucosubstances and proteins seems to be identical with the electron-dense substance found on the surface of developing cysticercus during electron-microscopical studies. It is considered to be a mimicry enabling the cysticerci to survive even in an immunologically unfavourable environment. Phospholipids were found in activated fibroblasts and in some cells of macrophage type on days 21 and 30 p.i. and in a large number in subtegumental cells of cysticercus on days 28-34 p.i. This phenomenon seems to be correlated with the increased activity of subtegumental cells of the larva in this period. In morphologically fully differentiated cysticerci, the reaction for phospholipids in subtegumental cells and distal cytoplasm was only feebly positive. Phospholipids were not detected in the rim of microtriches at any time after infection.