Aluminum adjuvants rapidly form into nodules in vivo. (A) A suspension of Alhydrogel in PBS. (B) Top left, a normal mouse liver; top right, liver of a mouse injected with Alhydrogel; bottom left, intestines of an uninjected mouse; bottom middle, intestines of a mouse injected with Alhydrogel; bottom right, leg muscle of a mouse injected with Alhydrogel. Photos taken 4 hours after injection. (C) At various times after intraperitoneal injection of 4 mg of Alhydrogel, nodules were collected and weighed. (D) At 4 hours after injection of 4 mg of Alhydrogel, Adju-Phos, aluminum potassium sulfate (Alum), or Imject Alum, nodules all form nodules within 4 hours in vivo. All experiments included at least 3 mice per group. Panel B was repeated more than 5 times. Panels C and D were repeated twice each.