Computer programs for the analysis of immunohistochemically labeled spinal cord sections

A microcomputer based image processing system has been developed to analyze the density of immunohistochemical labeling within neural tissue. The system permits the tracing of anatomical regions seen on a digitized image and the determination of the area and the mean gray level of all pixels lying within each defined region. Corrections are made for uneven screen illumination and for nonlinearity of the video camera's response to gradations in optical density. A standardization procedure ensures that the same level of incident illumination is used during each experiment. An example of an application of this system is described in which unilateral changes in immunohistochemical staining density were determined within the rodent spinal cord following partial spinal injury. This system provides a sensitive and objective means of analyzing such changes.