Tissue microarrays are constructed with small core biopsies of different tumors/ tissues. A core is obtained from the donor paraffin block of the tumor (a). A recipient paraffin block is prepared, creating empty cores (b). The cores are incorporated into the slots (c) until all are occupied (d). Glass slides are prepared and stained with a selected antibody (e). Microscopic examination reveals the different staining patterns of each core (f).