Fig. 4

Histologic examination of ovaries from different genotypes (amh+/+, amh +/− and amh−/−) and fecundity analysis. (A) Histology of the ovaries at 4 mpf. Representative sections of the whole ovaries from different genotypes are shown. The mutant ovary (amh−/−) contained much more PG follicles as compared with the controls (amh+/+ and amh+/−). (B) GSI in the control (amh+/−) and mutant (amh−/−) females at different time points (3–12 mpf). The mutants demonstrated higher GSI values after 3 mpf compared with the control (n = 8). The mutant females also showed enlarged abdomen at 12 mpf. (C) Receding folliculogenesis in female amh mutants. Histological analysis of the control (amh+/−) and mutant (amh−/−) ovaries from 2 to 12 mpf. The boxed areas were shown at higher magnification below. PG (stage I), primary growth follicles; PV (stage II), previtellogenic follicles; FG (stage III), full-grown follicles. (D) Analysis of follicle composition in the control (amh+/−) and mutant (amh−/−) ovaries. Two distant sections from each individual were chosen for follicle counting, and the numbers of PG, PV and EV-FG (stage III) follicles in each section were counted. The average of the two sections for each follicle stage was calculated to represent the individual (n = 5). (E) Mating performance and fecundity of the control (amh+/−) and mutant (amh−/−) females. Mating performance is defined as the percentage of successful spawning in each test (n = 8; 15 tests), and fecundity is defined as the number of eggs ovulated and released (n = 8). (F) Expression of vitellogenin genes (vtg1, 2, 4–7, and vtg3) in the liver of control (amh+/−) and mutant (amh−/−) (>4 mpf). * P < 0.05; ** P < 0.01. N.D., not detectable.