卵形鲳够免疫器官的早期发育

研究了卵形鲳鲹（Trachinotus ovatus）仔、稚鱼期间3种免疫器官的发生和发育过程。结果表明，3种免疫器官原基出现的先后顺序是头肾、脾脏和胸腺，出现时间分别为2日龄、3日龄和3日龄。其中，头肾的早期发育过程可分为原基形成期、造血功能发展期和泌尿功能退化期。进入稚鱼期后头肾的肾小管分布相对减少，表明头肾已不是主要的泌尿功能区。6-8日龄仔鱼脾脏中造血干细胞向红血细胞分化并产生大量未成熟红细胞。22日龄时脾脏组织体积进一步增大，内部血细胞参与血液循环。胸腺原基出现后胸腺细胞增多、体积增大，细胞嗜碱性不强。10-13日龄时胸腺细胞的嗜碱性增强，淋巴细胞开始增多，此时胸腺开始分区。20-22日龄稚鱼期结束时胸腺的内区和外区进一步分化，分区更为明显，表明胸腺进一步成熟。未发现胸腺和头肾之间淋巴细胞迁移的现象。

Development of immune organs at early stages of Trachinotus ovatus

A histological examination was conducted to study the ontogenetic development of 3 immune organs of Trachinotus ovatus at early developmental stages. The anlage of head kidney was the first organ to be observed at 2 day-post-hatch （dph）, and then followed by spleen （3 dph） and thymus （3 dph）. The developmental process for head kidney includes 3 stages which are anlage forming stage, developmental stage of hematopoiesis and degraded stage of urinary function. When the fish became postlarva （18~22 dph）, the distribution of renal tubules became less and its urinary function degraded. At 6~8 dph, the hematopoietic stem cells began to differentiate into large amount of immature red cells. At 22 dph, the spleen became larger and more mature, and the inner blood cells were involved in blood circulation. The number and size of thymus cells with weak basophilia grew after anlage of thymus appeared. At 10~13 dph, the basophilia of thymus cells and the number of lymphocyte grew, and the thymus began to differentiate to inner zone and outer zone. During the end of juvenile stage （20~22 dph）, the inner zone and outer zone became distinct, indicating the maturity of thymus. The transfer of lymphocyte between thymus and head kidney had not been observed.