Expression of Ad4BP/SF-1 in the spleen. Expression of Ad4BP/SF-1 was investigated using immunoblot (A) and immunohistochemical analysis (B, C, D, E, F, G, and H) using the antiserum to Ad4BP/SF-1. Total tissue lysates (25 μg) were prepared from spleen tissues of adult (Adult), E16.5 fetus (E16.5), and wild [B0 (Nor)] and KO [B0 (KO)] newborn mice. Adrenal glands (Adrenal) of adult mice were used as the positive control for detection of Ad4BP/SF-1. Molecular weight markers are indicated on the left. Arrows indicate signals for Ad4BP/SF-1. Immunohistochemistry was performed using mouse (B) and rat (C) splenic tissues, and perfused mouse (D, E, and F) and rat (G) spleen tissues. A tissue sample of human spleen was washed with PBS to remove erythrocytes and immunostained (H). Note that almost all positive nuclei are localized in the red pulp (r) but not in the white pulp (w) (B and C). Red and black asterisks in D, F, G, and H indicate venous sinuses and pulp vein, respectively. Arrowheads in E indicate the basement membrane of the venous sinus. Arrowheads in F indicate Ad4BP/SF-1 immunoreactive nuclei surrounding the white pulp. Ca, central artery. Scale bars: 50 μm in B, C, D, F, and H; 120 μm in E and G.