广东池塘培育四指马鲅亲鱼初次性成熟和苗种规模化繁育技术研究

采用组织切片和透射电镜技术对人工培育四指马鲅 (Eleutheronema tetradactylum) 鳃结构及其早期(1—35日龄)发育进行观察。结果显示，鳃耙列齿状，鳃丝梳状排列在鳃弓上，鳃小片排列在鳃丝两边。透射电镜下鳃小片主要由线粒体丰富细胞 (Ⅰ型和Ⅱ型)、扁平上皮细胞、柱细胞、血细胞、黏液细胞和未分化细胞组成。四指马鲅鳃早期发育显示，1日龄鳃原基形成；3日龄出现鳃弓，有扁平上皮细胞和血细胞；5日龄出现鳃小片，鳃小片上有柱细胞，基部有线粒体丰富细胞；18日龄鳃小片增多，鳃结构完善；35日龄鳃结构基本和成鱼一致。根据发育特点将其分为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，仔鱼主要靠鳍褶、皮肤和卵黄囊上的微血管进行呼吸；第2阶段 (4—17日龄) 为鳃结构分化、发育期，鳃耙、鳃弓、鳃丝、鳃小片逐渐形成，具备鳃基本的结构特点；第3阶段 (18—35日龄) 为鳃结构完善期，鳃组织发育主要体现在数量和形状的变化。

Low mtDNA Cytb diversity and shallow population structure of Eleutheronema tetradactylum in the East China Sea and the South China Sea

We investigated the structure and early development of gill tissue in artificially cultured Eleutheronema tetradactylum [1−35 d after hatching (DAH)] by histological section technique and transmission electron microscopy. The results show that the gill rakers were prick-shaped; the primary lamella on the gill arch were in a comb-like pattern; and the secondary gill lamella were evenly arranged on both sides of the primary lamella. The transmission electron microscopy shows that the secondary lamella consisted of mitochondria-rich cells (two types) pavement cells, pillar cells, blood cells, mucous cells and non-differentiated cells. According to the early development, the gill-primordia appeared on 1 DAH; the primitive gill arch appeared on 3 DAH, containing pavement cells and blood cells; the secondary gill lamella appeared on 5 DAH, and the pillar cells were on the secondary gill lamella; there were scattered mitochondria-rich cells at the base of the secondary lamella which increased and whose structure was basically formed on 18 DAH; the gill structure was basically identical to the adult fish on 35 DAH. The development could be divided into three stages: Stage I was organ-primordium formation (0−3 DAH). During this stage, the gill-primordia formed but undifferentiated, and the respiration was primarily via the finfold, skin and microvascular surface of yolk-sac. Stage II was characterized by differentiation and development of gill filaments (4−17 DAH). During this stage, the gill arches, filaments, secondary gill lamella and gill rakers developed gradually and the basic structure and morphology of the gill were established. During Stage III (18−35 DAH), the gill development was mainly the change in number and shape.