Whole-mount BrdU detection after a 24 hour pulse of ST induced specimens. A. Full view of a tetrathyridium. B. Close-up of the scolex of the specimen shown in 2A. C. Close-up of the border of the body wall of a tetrathyridium. The broken line indicates the limit of the body wall. D. Initiation of segmentation; arrowheads indicate periodic accumulations of BrdU+ cells. Anterior is to the right. E. Early segments of adult worm. F. Later segment of adult worm, with genital primordium (large arrow) and testis primordia (asterisks). G. Scolex of adult worm. Small arrows in all figures indicate rare BrdU+ cells in the cortical parenchyma. cp, cortical parenchyma; mp, medullary parenchyma; s, sucker; st, sub-tegument. Note that the tegument was previously removed. Bars represent 1000 μm in A, 200 μm in B, D and G, 50 μm in C and E, and 100 μm in F.