Fig 1.
Scoring categories used for assessing the number of silica-laden macrophages (SLMs) within badger tissues.
Under polarized light, SLMs contrast brightly against the darker background tissue. For a higher magnification view of SLMs, see also Figs 2 and 3.
Fig 2.
Silica-laden macrophages (SLMs), lung, badger.
Multifocal interstitial accumulations of macrophages engorged with crystalline material. (A) Crystalline material has a light brown color and finely granular to spicular appearance in routinely stained sections. H&E. x200. (B) Crystalline material is strongly birefringent under polarizing light, consistent with silica and silicates. H&E, x200. (C) No evidence of associated collagen deposition on Massons trichrome stain (stains collagen blue). x200.
Fig 3.
Silica-laden macrophages (SLMs), bronchial lymph node, badger.
Focally-extensive aggregation of SLMs in the absence of collagen deposition. (A) SLMs are strongly birefringent under polarizing light. Massons trichrome stain. x100. (B) No evidence of associated collagen deposition on Massons trichrome stain (stains collagen blue). x100.
Fig 4.
Distribution and cumulative silica-laden macrophage (SLM) score across badger lymph nodes, tonsils, liver and spleen.
Bars represent the cumulative SLM score per tissue across the study population of 60 badgers.
Fig 5.
Bar chart comparing cumulative silica-laden macrophage (SLM) scores in tissues from badgers with positive and negative M. bovis infection status.
Bars represent the cumulative SLM score per tissue across groups of M. bovis positive (n = 30) and M. bovis negative (n = 30) individuals.
Table 1.
Distribution of silica-laden macrophage (SLM) scores in lymph nodes and lung tissue of M. bovis positive and negative badgers.
Fig 6.
Bar chart comparing cumulative silica-laden macrophage (SLM) scores in tissues from badgers with low and high SLM lung scores.
Bars represent the cumulative SLM score per tissue across groups of individuals with SLM lung scores of either ‘1’ (n = 33) or ‘2’ (n = 27).
Table 2.
Distribution of silica-laden macrophage (SLM) scores in lymph nodes of badgers with a high and low lung SLM score, respectively.
Fig 7.
Grouped bar graph illustrating the proportion (in %) of badgers in each scoring category (x-axis) among age classes.
Given are examples of score distribution among age classes (young (n = 10); adult (n = 31); old (n = 19)) for an intrathoracic (A) and extrathoracic (B) lymph node (LN). (A) Left tracheobronchial LN; (B) Left popliteal LN. Differences in distribution between age classes were statistically significant (Table 3).
Table 3.
The distribution of silica-laden macrophage scores in badger lymphatic tissues and lung among age classes.
Fig 8.
Validation of badger lymph node scoring categories.
Boxplots represent the total number of silica-laden macrophage (SLM)-positive fields of lymph nodes within each scoring category 1–3 (see Fig 1). 10 slides were examined per category, and 1000 fields assessed per slide. A positive field was defined as one that contained at least one SLM. One outlier has been omitted from this graph (Scoring category 3: 867).