Cestode calcareous corpuscles: Phosphate relationships, crystallization patterns, and variations in size and shape

Abstract

Calcareous corpuscles isolated from larval Echinococcus granulosus yielded similar average phosphate values when worms of Chilean, Argentinian, Australian, and Lebanese provenience were analyzed contraindicating the existence of distinct geographic strains of the parasite. Instead, the observed variations are more likely due to nutritional differences. Considerable variations in phosphate content of calcareous corpuscles were encountered in analyses of both individual larval and adult Taenia taeniaeformis, the variations being somewhat more pronounced in the latter than in the former. In general, corpuscles isolated from laboratory-infected cats contained significantly less phosphate than those taken from stray cats, again presumably indicating the influence of the nutrition of the host on the phosphate content of the calcareous corpuscles. Isolated calcareous corpuscles incorporated variable amounts of phosphate, depending upon the following factors: pH of the medium, isolation procedure, species of tapeworm, and ratio between the amount of corpuscles to the volume of incubation fluid. Crystallographic studies showed that the originally amorphous corpuscles of T. taeniaeformis gave a weak dolomite-like pattern after 180 days of uninterrupted heating to 150 °C. Definite dolomite formation was induced by heating to 180 °C. The dolomite was stable up to 400 °C, but decomposed readily at 450 °C. Hydroxyapatite appeared first upon heating to 400 °C and remained stable up to the highest temperature tested, 900 °C. The heat-induced crystallization patterns of corpuscles from ten additional tapeworms were determined. Especially remarkable was the fact that in two species ( Cysticercus bovis and Cysticercus tenuicollis) a weak, but definite dolomite pattern was found after ethylenediamine isolation, without the necessity of applying additional heat. Considerable variations in size and shape between corpuscles of various species were found. Echinococcus multilocularis, for example, had giant corpuscles with diameters up to 34 μ, while those of Priapocephalus sp. measured usually between 2 and 4 μ. Some species had predominantly round corpuscles, others oval or irregularly shaped ones. Where comparisons between larval and adult corpuscles were possible no significant differences were found in most cases. The only exception was Taenia saginata where the corpuscles of the adult were definitely smaller than those of the larva.