Thyroid hormone surges during milkfish metamorphosis.
Both thyroxine (T4) and triiodothyronine (T3) were detected in fertilized eggs and larvae of milkfish. The concentration of T4 was lower than that of T3 only in fertilized eggs and newly-hatched larvae. The total body concentrations of both thyroid hormones decreased after hatching. The T4 concentration fluctuated at relatively low levels during the first week after hatching, increased gradually during the next 2 weeks and was highest in 4-week-old larvae. On the other hand, T3 was undetectable in samples taken between days 3 and 11, showed a gradual increase beginning on day 13 and was highest in 27 day old larvae. The concentrations of both T4 and T3 declined again in 31-day-old juveniles. The peak corresponds with the development of silver coloration in hatchery-reared milkfish and the inshore milkfish and the inshore migration of larvae in the wild, suggesting a role for thyroid hormones during early development of this species.
Suggested Citationde Jesus, E. G. (1994). Thyroid hormone surges during milkfish metamorphosis.
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