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Table 1 Criteria for grading lung fibrosis

From: Dynamic assessing silica particle-induced pulmonary fibrosis and associated regulation of long non-coding RNA expression in Wistar rats

Grade of fibrosis

Histological features

0

Normal lung

1

Minimal fibrous thickening of alveolar or bronchiolar walls with a few of inflammatory cells

2

Between 1 and 3

3

Moderate thickening of walls without obvious damage to lung architecture

4

Between 3 and 5

5

Increased fibrosis with definite damage to lung structure and formation of fibrous bands or small fibrous masses

6

Between 5 and 7

7

Severe distortion of structure and large fibrous areas; Typical silica nodules formed by collagen fibers.

8

Total fibrous obliteration of the field