Assessment of mast cells degranulation in rainbow trout (Oncorhynchus mykiss Walbaum) by means of gray level and texture analysis (Gray Level Correlation Matrices)

Degranulation of intestinal mast cells in rainbow trout (Oncorhynchus mykiss Walbaum) was studied by means of image analysis technique. Two strips from the same intestinal segment from ten clinically healthy trout were sampled. One was immediately mounted in an organ bath, treated with compound 48/80 and then processed, as the remnant untreated strip, for light microscopy. Colour pictures taken from each section were converted in their gray levels RGB stacks equivalent and in 8 bits gray levels. Five granular cytoplasm areas of mast cells (MCs) for each section were analysed for the following parameters: mean gray values and Gray Level Correlation Matrices parameters. All RGB channels and the 8 bit gray levels transformed images showed higher mean gray level values after compound 48/80 exposure (Anova, p<0.01). Only two channels (Red and Green) and the 8 bit gray levels transformed images of a unique texture parameter (contrast) appeared to be significantly higher after compound 48/80 exposure (Anova, p<0.05). Red channel and Blue channel means gray level values were able to discriminate between not degranulated and degranulated MCs. The described model represents a promising alternative in mast cell research.