We documented the differentiation and development of the gill and the relationship between gill structure and function in Trachinotus ovatus using histology and scanning electron microscopy. Development of the gill was divided into three stages in the larvae and juveniles. Stage I included organ-primordium formation between 0-3 days after hatching (DAH). During this stage, gill-primordia were present but undifferentiated, there were no gill rakers, and respiration occurred primarily via the finfold, skin, and the microvascular surface of the yolk-sac. Stage II occurred between 4-17 DAH and was characterized by differentiation and development of gill filaments. Gill arches, filaments, secondary gill lamella, and gill rakers developed gradually and the basic structure and morphology of the gill were established. Stage III was initiated at 18 DAH, at which time the gill organs (e.g., arches, filaments, secondary gill lamella, and rakers) resembled the adult in terms of morphology and function. The total number of gill filaments increased with the increasing body weight and body length in larvae and juveniles. Thus, the single secondary gill lamella area and total respiratory area also increased with an increase of body weight. The differentiation and development of the gill was in accordance with growth, development, and function in larval and juvenile T. Ovatus.%采用组织学和扫描电镜等方法,研究了卵形鲳鲹(Trachinotus ovatus)胚后发育阶段鳃的分化和发育及其结构和功能的关系.观察发现,仔稚鱼鳃的早期发育可分为3个阶段:第1阶段(0～3日龄)为原基期,鳃原基形成但未分化,鳃耙未出现,仔鱼主要依靠鳍褶、皮肤和卵黄囊上的微血管进行呼吸；第2阶段(4～17日龄)为鳃丝分化、发育期,鳃弓、鳃丝、鳃小片、鳃耙逐渐形成,具备鳃的基本结构和形态特点；第3阶段(18日龄之后)为鳃器官生长发育完善期,鳃弓、鳃丝、鳃小片、鳃耙发育完善,鳃的形态和功能与成鱼相似.进一步研究发现,鳃丝总数随仔稚鱼全长和体质量的增加而增加,单个鳃小片面积和总呼吸面积随仔稚鱼体质量的增加而增大.结果表明,卵形鲳鲳鲹的分化和发育是与仔、稚鱼的生长、形态发育和功能的完善相一致的.
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