볼락, Sebastes inermis 자어의 초기 발달동안 갑상선의 분화 및 발달

Abstract

The rockfish Sebastes inermis is one of the scorpaenid fishes giving birth to yolk-sac larvae. It is distributed around the south of Korea and is one of the main species cultured for breeding improvement. The development of thyroid tissue in larvae was histologically examined during early development of S. inermis, and the relationship between thyroid follicle differentiation and growth was also studied. Total length (TL) and body weight (BW) of larvae at birth were 5.7±0.1 mm and 0.9±0.3 mg, respectively. The larvae transformed to juveniles during periods from 20 to 30 days after parturition. The primary thyroid follicle was observed histologically in newborn larvae after parturition. The larvae have one thyroid follicle primordium, differentiated between the basibranchial bone and ventral aorta at the base of the first gill arch. At that time, thyroid follicle diameter (TFD), thyroid follicle number (TFN), and thyroid cell height (TCH) were 6.2±0.3 µm, 1.3±0.1 pieces/inds., and 1.2±0.1 µm, respectively. TFN, TFD and TCH were significantly increased during 0~5 days after parturition (P⁄0.05). Following 5 days after parturition, however, both TFD and TFN continuously increased during early development, but TCH did not change during the same period.