Fig. 1.

Recruitment of neutrophils to brain parenchyma and permeability of the blood–brain barrier to endogenous IgG 4 h after focal inflammation during postnatal period. Neutrophils were recruited to the site of the intracerebral IL-1β (1ng) injection as shown in representative spatial maps of neutrophil distribution in the brain (A). Recruitment of neutrophils 4 h after the injection was highest at P14 (A, B) and they were found to enter the brain parenchyma as well as filling the vessel lumen. Photomicrographs in (A) show neutrophils (brown; anti-neutrophil serum) and vessels (pink; laminin) within the striatal injection site (marked by red ‘x’ in the P7 spatial map). Intracerebral injection of 1 ng IL-1β and subsequent neutrophil recruitment was associated with increased blood–brain barrier permeability to endogenous IgG at P14, but not at P7, P21 and P56 as shown in the photomicrographs in (C). Scale bar = 50 µm. ^***p < .001. ^###p < .001 vs. all parenchyma values. P7: n = 4, P14: n = 5, P21: n = 4 and P56: n = 3. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)