Image analysis of vocal fold histology

To visualize the concentration gradients of collagen, elastin and ground substance in histologic sections of vocal folds, an image enhancement scheme was devised. Slides stained with Movat's solution were viewed on a light microscope. The image was digitally photographed. Using commercially available software, all pixels within a color range are selected from the mucosa presented on the image. Using the Movat's pentachrome stain, yellow to yellow-brown pixels represented mature collagen, blue to blue-green pixels represented young collagen (collagen that is not fully cross-linked) and black to dark violet pixels represented elastin. From each of the color range selections, a black and white image was created. The pixels not within the color range were black. The selected pixels within the color range were white. The image was averaged and smoothed to produce 256 levels of gray with less spatial resolution. This new grey-scale image showed the concentration gradient. These images were further enhanced with contour lines surrounding equivalent levels of gray. This technique is helpful to compare the micro-anatomy of the vocal folds. For instance, we find large concentration of the collagen deep in the mucosa and adjacent to the vocalis muscle.