A nucleus that is blue/black will specifically stain what?
{'header': ['Stain', 'Common use', 'Nucleus', 'Cytoplasm', 'Red blood cell (RBC)', 'Collagen fibers', 'Specifically stains'], 'page_title': 'Histology', 'section_title': 'Common laboratory stains', 'caption': 'Common laboratory stains', 'rows': [['Haematoxylin', 'General staining when paired with eosin (i.e. H&E)', 'Orange, Cyan Blue or Green', 'Blue/Brown/Black', 'N/A', 'N/A', 'Nucleic acids—blue ER (endoplasmic reticulum)—blue'], ['Toluidine blue', 'General staining', 'Blue', 'Blue', 'Blue', 'Blue', 'Mast cells granules—purple'], ["Masson's trichrome stain", 'Connective tissue', 'Black', 'Red/pink', 'Red', 'Blue/green', 'Cartilage—blue/green Muscle fibers—red'], ["Weigert's elastic stain", 'Elastic fibers', 'Blue/black', 'N/A', 'N/A', 'N/A', 'Elastic fibers—blue/black'], ["Heidenhain's AZAN trichrome stain", 'Distinguishing cells from extracellular components', 'Red/purple', 'Pink', 'Red', 'Blue', 'Muscle fibers—red Cartilage—blue Bone matrix—blue']]}