Table 3: Histological scoring system used on rainbow trout intestinal cross sections.

Score Appearance
Lamina Propria of Simple Folds
1 Thin and delicate core of connective tissue in all simple folds.
2 Lamina propria slightly more distinct and robust in some of the folds.
3 Clear increase in lamina propria in most of simple folds.
4 Thick lamina propria in many folds.
5 Very thick lamina propria in many folds.
Connective Tissue between Base of Folds and Stratum Compactum
1 Very thin layer of connective tissue between base of folds and stratum compactum.
2 Slightly increased amount of connective tissue beneath some of mucosal folds.
3 Clear increase of connective tissue beneath most of the mucosal folds.
4 Thick layer of connective tissue beneath many folds.
5 Extremely thick layer of connective tissue beneath some of the folds.
Vacuoles
1 Large vacuoles absent.
2 Very few large vacuoles present.
3 Increased number of large vacuoles.
4 Large vacuoles are numerous.
5 Large vacuoles are abundant and present in most epithelial cells.