Localization of TGF-α in macrophages. Cryosection of a macrophage from a nasal polyp labeled for TGF-α. A few granules are labeled for TGF-α (arrows). Nucleus, (n); bundles of collagen (C). Inset is a higher magnification of the marked granules (asterisk) to show the gold labeling. Bars = 500 nm, inset = 100 nm.