EFFECTS OF COLCHICINE ON THE NUMBER OF T2 VESICLES IN THE TEGUMENT OFFASCIOLA-HEPATICA

The role of microtubules in the secretory processes in the tegument of adult trematode Fasciola hepatica L. is studied by estimating the eff ects of colchicine, a substance known to disrupt microtubules, on the number of T2 vesicles. Tissue slices of the worm are incubated in Hedo n-Fleig medium with or without 5 x 10(-4)M colchicine. The dynamics of the colchicine-provoked secretory block is examined by morphometry on samples processed for electron microscopy. T2 vesicles are estimated as a total number or separately within three levels (apical, sub-apica l and central) of the distal tegument. The secretory block is demonstr ated as reduction in the total number of T2 vesicles. The separate cou nting within three levels of the distal tegument demonstrates in contr ol samples a trend of sub-apical condensation of T2 vesicles. This pat tern of T2 distribution remains unchanged in colchicine-treated sample s in spite of the reduction of the mean T2 counts within each of the l evels examined. The data illustrate the role of microtubules in both t he tegumental transport of secretory vesicles and the stratification o f the organelles within the tegument.