The expected PCR product size was

1000 base-pairs (bp) for both assays. For visualisation of PCR products, 5× DNA loading buffer (Bioline, London, click here UK) was added to the PCR reaction and 5 μl was loaded on a 1% agarose gel containing SYBR® Safe nucleic acid stain (Invitrogen). Electrophoresis in 1× Tris–acetate–EDTA buffer was conducted for 1 h at 100 V, and the gel was imaged using a Safe Imager™ blue-light transilluminator (Invitrogen) and a gel documentation system with GeneSnap software (Syngene, Cambridge, UK). Tissues fixed in 10% neutral-buffered formalin were cut into 4 μm sections and stained with Mayer’s haemalum and eosin. Slides were examined for the integrity GSK-3 activation of worm sections and the immune response, and photographed on a Microphot-FX digital microscope (Nikon). One nodule was taken from each of 15 cattle of a broad age range and examined. Of these 15 cattle with nodules, 7 sections of aorta wall were also examined. Two slides, one from the nodule of a 3-year-old female and the other from the aorta wall of a female of at least 10 years of age, were examined for Fe2+, Ca2+ complexes, and endothelial cells with Prussian blue, von Kossa, and Factor VIII-related antigen stains, respectively. This allowed visualisation of Fe2+ in haemosiderin

from ingested erythrocytes if present, Ca2+ in mineralised tissue, and the location of O. armillata adult worms with respect to the endothelial-lined microvasculature others and lymphatic vessels. All statistics

were performed in PASW Statistics 17.0 (SPSS Inc., Chicago, IL, USA). Frequency data were analysed by Fisher’s exact test, whereas medians of independent count data were compared using the Mann–Whitney U-test or the Kruskal–Wallis test. Paired data were subjected to the log10(x + 1) transformation to normalise the distribution, and analysed using a paired t-test. The critical probability for statistical significance was P < 0.05. Adult worms of O. armillata were found in 90.7% (49/54) of the cattle examined ( Table 1). Of those animals positive for adult worms, 65.3% (32/49) had nodules in the aorta wall ( Table 1). The sampled animals were divided into four predetermined age categories, and the prevalence of adult parasites and nodules was analysed across the age distribution. There was no significant association between age and either the presence of adult worms or aortic nodules (P > 0.05, Table 2). Only 6 bulls were examined in this study, reducing the power of any analysis by sex. Although the prevalence of nodules was twice as high in females (69.8%) than in males (33.3%), this was not statistically significant (Fisher’s exact test, P = 0.16). Only 24.5% (12/49) of the animals with adult parasites in the aorta had detectable patent infections (i.e.