Fig 1: Apicobasal Cell Polarity and BTB Are Disrupted in Adult Rac1 cKO Sertoli Cells(A–N) Three-month-old (P90) (A)–(L) and 1-month-old (P30) (M and N) control Dhh-Cre;Rac1flox/+ (A, C, E, G, I, K, and M) and Dhh-Cre;Rac1flox/flox cKO (B, D, F, H, J, L, and N) testes. (E’)–(N’) are higher-magnification images of the boxed regions in (E)–(N). Dashed outlines indicate tubule boundaries.(A and B) GATA1+/SOX9+ Sertoli cell nuclei (arrows) in controls (A) are localized basally, but cKO nuclei (B) are both basally and centrally localized within the tubule.(C and D) Relative to controls (C), Vimentin is localized ectopically throughout the entire cKO Sertoli cell (D).(E and F) SCRIB is localized to the BTB and basal Sertoli compartment in both control (E) and cKO (F) testes. However, phalloidin staining is localized ectopically throughout the entire cKO Sertoli cell (see also I–L).(G and H) CLDN11 and CTNNB1 are enriched in a specific ring-like network (BTB; arrows in G’) in control Sertoli cells (G), but they are localized throughout the entire cKO Sertoli cell (H).(I and J) PARD3 is normally enriched at the BTB and apical ES in controls (I), but it is localized throughout the entire cKO Sertoli cell (J). Note that PARD3 is also localized to the BTB.(K and L) ITGB1 is localized diffusely throughout cKO tubules (L), in contrast to specific apical ES staining in controls (K); however, basement membrane, spermatogonial, and interstitial staining is still observed in both control and cKO testes.(M and N) One-month-old (P30) control (Dhh-Cre;Rac1flox/+) (M) and cKO (N) testes injected with biotin (and detected with streptavidin). cKO testes showed widespread infiltration of biotin deep into tubule lumens (arrows). Scale bar, 50 µm.See also Figure S4.