Fig. 3. Fgf9^-/- XY gonads are smaller than Fgf9^+/- XY littermates by 12.5 dpc. (A) Using PECAM labeling to define the size of the gonad, it was observed that the width of Fgf9^-/- XY gonads was less than Fgf9^+/- XY gonads and roughly the same as XX gonads at 12.5 dpc. (The width at the gonad's center is indicated by brackets.) (B) The mean width of gonads from XY individuals (+/+ and +/-) was 277.4±12.5 µm (n=9). Gonads from Fgf9^-/- XY littermates were significantly smaller (Student's t-test P<0.01), with a mean width of 202.9±14.2 µm (n=6). Gonads from Fgf9^-/- XX individuals had a mean thickness of 187.3±6.8 µm (n=6) and were not significantly smaller than wild-type XX gonads (193.5±8.5 µm, n=8, P>0.05). Error bars indicate s.e.m. (C) The mean lengths of gonads from XY (+/+ and +/-) and Fgf9^-/- XY individuals were not significantly different from each other (1016.3±28.4 µm and 981.5±30.2 µm, respectively, P>0.05). Additionally, the mean lengths of gonads from XX (+/+ and +/-) and Fgf9^-/- XX individuals were not significantly different from each other (997.5±13.8 µm and 1025.0±12.7 µm, respectively, P>0.05).