The effect of different sensitisation/challenge combinations on sub-epithelial collagen deposition. The area of sub-epithelial collagen/unit lumen perimeter was quantitated in mouse airways using image analysis of MSB stained sections. (A) Mean values for all suitable airways in each experimental group were compared. The numbers of mice/total airways analysed per group were: saline sensitised/saline challenged (NS/NS) 8/89, saline sensitised/ovalbumin challenged (NS/Ova) 9/95, ovalbumin sensitised/saline challenged (Ova/NS) 7/88 and ovalbumin sensitised/ovalbumin challenged (Ova/Ova) 11/147. (B) Mean values for all suitable larger (perimeter>1000 μm) airways in the same mice were also compared. The numbers of airways analysed were NS/NS 48, NS/Ova 30, Ova/NS 22 and Ova/Ova 39. * p < 0.01 compared with the mean of the controls.