Comparison of HIF-2α and CD31 expressions among WT, kd/kd, and kd/kd::Tie-1-Cre mouse spleens. (A) Left and center panels: Structures of microcapillary in the spleen of WT (i) and kd/kd (ii) were examined by the injection of TRITC-conjugated lection. Note that lection-bound cells form capillary-like structures in red pulps. *Area of white pulps in spleens. Bar represents 500 μm. Right panel: Fluorescent intensity of TRITC was measured in 9 separate fields of view in the red pulp area. The fluorescent frequency measured in a field of WT was normalized to a value of 1 and the average of relative fluorescent intensity was indicated (**P < .01). Error bars represent SD. (B) Left columns (TRITC; i, iv, and vii) represent magnified view of rectangle area shown in panel A. Middle columns (FITC; ii, v, and viii) represent fluorescent immunohistochemistry of HIF-2α in spleen. Right columns (iii, vi, and ix) represent merged pictures to examine HIF-2α-positive microcapillaries (yellow color). Sections from WT (i-iii) and kd/kd (iv-vi) mice are shown. (vii-ix) Normal rabbit IgG was used in WT sections as a negative control. *Area of white pulps. Bar represents 100 μm. (C) Histochemical staining was undertaken in spleens using hematoxylin and eosin (HE) (i-iii) and anti-CD31 antibody (iv-vi). Left panels, middle panels, and right panels represent WT, kd/kd, and kd/kd::Tie-1-Cre mice, respectively. W and R represent white pulp and red pulp, respectively. Bar represents 100 μm.