[Gonadal ontogenesis and sex differentiation in the sea bass, Dicentrarchus labrax, under fish-farming conditions].

The histology of the different stages of gonadal development (appearance of PGC, edification of gonad primordium, organization of an undifferentiated gonad, testicular or ovarian development) has been studied in fingerlings and juveniles of sea-bass in fish-culture conditions. Sex differentiation with a caudo-cranial gradient was direct and more in accordance with length than with age. Ovarian and testicular differentiation occurred in fish 11 to 23 months old and from 90 to 187 mm SL. Testis ova were frequently observed.