FIGURE 2.

Abnormality in ductal branching in the Klf6-deficient prostate epithelium. Morphological ductal aberrations in Klf6-deficient anterior prostates were first observed at P5 and retained in adult mice. Light microscopy images (A, B, E, and F) and H&E staining (C and D) of Klf^f/fNkx3.1^+/+ (A, C, and E) and Klf^f/fNkx3.1^Cre/+ (B, D, and F) from P5 and 1-year-old anterior prostates that were microdissected prior to imaging. Only one side of the symmetrical anterior lobe was imaged, and three mice were imaged from each stage. Branching was visible in both microdissected (arrow, A) and H&E-stained (arrow, C) P5 sections from Klf^f/fNkx3.1^+/+ but not in Klf^f/fNkx3.1^Cre/+ (B and D). Ex vivo ultrasound imaging allowed visualization of the interior of anterior prostate of Klf^f/fNkx3.1^+/+ (G) that appears dense and white due to extensive epithelial infolding in the ducts, and the single layer of while epithelial lumen that outlines the main ducts of Klf^f/fNkx3.1^Cre/+ mice (H). Arrowhead (in H) points to the significantly enhanced luminal space present within the main duct of Klf^f/fNkx3.1^Cre/+ anterior prostate. H&E staining of prostates obtained from 6-month-old (I and K) Klf^f/fNkx3.1^+/+ and (J and L) Klf^f/fNkx3.1^Cre/+ mice. Note that the widest region at the base of Klf^f/fNkx3.1^+/+ prostate (K) fits into the field of view, whereas the narrowest region of Klf^f/fNkx3.1^Cre/+ prostate (L) does not fit into the field of view. Epithelial infolding that spans the lumen was more extensive in Klf^f/fNkx3.1^+/+ prostates (arrow, I) than Klf^f/fNkx3.1^Cre/+ prostates (arrow, J). Insets represent higher magnification of the regions marked by the dotted square in K and L, respectively, that revealed nuclei with normal characteristics. Immunofluorescent staining of Klf6 expression in prostate tissues obtained from 8-week-old Klf^f/fNkx3.1^+/+ (M and O) and Klf^f/fNkx3.1^Cre/+ (N and P) mice. Klf6, which is a transcription factor, was highly localized to the nuclei of Klf^f/fNkx3.1^+/+ prostate epithelium (arrows, O), and depletion of Klf6 in the Klf^f/fNkx3.1^Cre/+ prostate was confirmed by the absence of green signal in the nuclei (arrowhead, P). I, J, M, and N, low magnification and high magnification (K, L, O, and P) of respective images. Bar in A, 500 μm for A and B, 1000 μm for E and F, and 750 μm for G and H. Bar in C, 50 μm for C and D. Bar in K, 200 μm for I and J and 100 μm for K–N. Bar in O, 50 μm for O and P.