The angiogenic responses induced by histamine and serotonin initially resembled that induced by VEGF-A165 but were transient. (A) Macroscopic appearance of progression and subsequent regression of angiogenesis with time in Nu/Nu mice implanted with histamine- and serotonin-containing pellets vs control pellets; (Ba-c) Angiogenic responses induced by histamine at 1, 5, and 15 days after implantation, respectively. Note characteristic MV at 1 day, vessel remodeling at 5 days, and striking vessel regression at 15 days. (Bd-f) Angiogenic responses induced by serotonin at 3, 7, and 21 days after implantation, respectively. Prominent MV are present at 3 days, which undergo remodeling thereafter (7 days) and regression (21 days). One-micron-thick, Giemsa-stained Epon sections.31 Magnification bars, 50 μm. Data are representative of 4 mice in each group. (C) Tissues adjacent to pellet implant sites were immunostained with an antibody against CD31. Mean vessel density was calculated with Image J software (ten 20× fields, 4 animals per group). ***P < .001; **P < .01; *P < .05, Student t test.
