canada balsam: yellow transparent exudate of the balsam fir; used as a transparent cement in optical devices (especially in microscopy) and as a mounting medium
chemical: material produced by or used in a reaction involving changes in atoms or molecules
anterior cerebral artery: one of two branches of the internal carotid artery; divides into two branches that serve (1) the thalamus and (2) parts of the frontal and parietal cortex