Fig. 5. Constitutive Notch signaling restricts Leydig cell differentiation throughout fetal gonad development, but cannot change the fate of differentiated Leydig cells.
The coelomic domain of the gonad is upwards, anterior is leftwards and posterior is rightwards. (A–D) H&E staining of mouse testis sections at P1, with (A,B) or without (C,D) immunostaining for 3β-HSD (black) in RosaNotch; Sf1-cre gonads (B,D) compared with gonads from mice carrying only one of the two transgenes (A,C). Spindle shaped cells increased in RosaNotch; Sf1-cre gonads (green arrows in D), whereas Eosin-staining Leydig cells (LC) declined. (E–H) Immunofluorescent staining for LHX9 (red, nuclear staining; cytoplasmic staining is nonspecific background) and DNA (Syto13, blue in E,F) or NICD (green in G,H) shows increased LHX9-positive cells in RosaNotch; Sf1-cre gonads, some of which were expressing Notch (white arrows in H, yellow staining cells). Broken lines outline testis cords. (I) RosaNotch; Hs-cre mice were heat-shocked at 13.5 dpc, after Leydig cell differentiation is initiated. At 15.5 dpc, many 3β-HSD-positive cells were detected (red), some also expressing NICD (green). Scale bars: 20 μm.