HISTOPATHOLOGY OF THYROIDS AND LIVERS OF RATS AND MICE FED DIETS CONTAINING BRASSICA GLUCOSINOLATES

Abstract

A histopathological comparison was made of thyroid and liver tissue from weanling mice and rats fed six different diets. The experimental diets contained mustard or rapeseed meal (RSM) varieties of high glucosinolate content, namely, Oriental mustard (Brassica juncea), Yellow Sarson (B. campestris), Target (B. napus) and Fe-treated Target (glucosinolate hydrolyzed by FeSO4). The two control diets contained a low glucosinolate variety of rapeseed meal, Bronowski (B. napus), or casein to provide approximately 20% dietary protein. Seven mice and seven rats were fed each diet 4 and 6 weeks, respectively. Both body growth rate and the histopathology of the thyroid gland were affected by the inclusion of rapeseed meals in the diet. The effect was more marked in rats than in mice. Whereas the high glucosinolate-containing RSM (cult Target) diet produced poorest performance in rats (P < 0.01) and mice (P < 0.05), the low glucosinolate RSM (cult Bronowski) diet was as efficiently utilized as the casein diet. Epithelial cell heights of the thyroid follicles were increased in the mice and rats fed Target RSM, but only rats showed a high degree of papillary formation. Liver involvement at the microscopic level was slight. The measurement of epithelial cell height showed most promise as an accurate indicator of cell size.