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Fig. 6. Acclimation induces gonadal maturity in males. The relative number of
spermatogonia, spermatocytes and spermatids/sperm present in the testis were
assessed in five experimental groups. Jul, fish captured in July; Accl.1, fish
captured in July and acclimated for 30 days at 28°C (constant photoperiod
and water conductivity); Sept, fish captured in September; Accl.2, Fish
captured in September and acclimated for 30 days at 28°C (constant
photoperiod and water conductivity); Nov, fish captured in November. Testes of
males freshly captured in July have spermatogonia and spermatocytes. After
acclimation (grey) the cell profile changed and resembled a mature male,
presenting almost 40% of advanced germ cells (spermatids and sperm). The
experiment was repeated with a group of fish collected in September, with
similar results. White bars, spermatogonia; hatched bars, spermatocytes; black
bars, spermatids and sperm.