四指马鲅淋巴器官发育组织学观察

采用石蜡组织连续切片和HE染色技术,对1~60 dph(Days post hatching)四指马鲅(Eleutheronema tetradactylum)的淋巴器官个体发育进行研究,描述了淋巴器官发育特点及组织学特征。结果显示,在盐度为9.0±0.5,水温为(28±2)℃条件下,3 dph胸腺原基出现,由4~6层未分化干细胞和淋巴母细胞样的细胞组成;胸腺发育迅速,主要由淋巴细胞填充;至25 dph皮质区和髓质区分明显,胸腺发育基本完成。3 dph头肾原基形成,由前肾管和少量造血干细胞组成;5 dph胸腺淋巴细胞向头肾迁移,头肾开始淋巴化;随着鱼体生长,造血干细胞分化成不同类型细胞;18 dph前肾管开始退化,至53 dph完全消失,头肾主要由网状内皮系统支持下的淋巴造血组织构成。7 dph脾脏原基形成,至16 dph开始淋巴化;脾脏内皮系统较头肾发达,但其发育速度较胸腺和头肾慢,淋巴细胞明显少于胸腺和头肾。研究表明,四指马鲅淋巴器官原基出现及淋巴化的顺序是胸腺、头肾、脾脏。免疫淋巴器官结构及功能尚未发育完善,可能是四指马鲅在变态期间幼体死亡率高的主要原因之一。

Histological Observations on the Early Development of Lymphoid Organs in Eleutheronema tetradactylum

This work focused on the histological study of the ontogeny of lymphoid organs by paraffin tissue sections and HE staining techniques in Eleutheronema tetradactylum,from 1 to 60 dph(day post hatching).The results showed that in the conditions of salinity 9.0±0.5 and water temperature(28±2)℃,thymus primordium appears at 3 dph that composed of 4~6 layers of undifferentiated stem cells and lymphocyte-like cells;thymus differentiated rapidly and mainly filled with lymphocytes;at 25 dph,the cortex and medulla are clearly distinguished and thymus development was basically completed.Similarly,the head kidney primordium formed at 3 dph,it consists of pronephric tubules and a few of hematopoietic stem cells;at 5 dph,the head kidney began to lymphatize when the thymic lymphocytes migrate there,and hematopoietic stem cells differentiated into different types of cells as the fish grew;at 18 dph,pronephric tubules began to degenerate and disappeared completely until 53 dph,when the head kidney is mainly composed of lymphopoietic tissue supported by reticular endothelial system.At 7 dph,the spleen primordium appears and begins to lymphatize obviously until 16 dph.The endothelial system of spleen is more developed than that of head kidney,but its development speed is significantly slower than thymus and head kidney,and lymphocytes are less than in the thymus and head kidney.These observations suggested that the respective lymphoid organs primordium becomes the thymus,head kidney and spleen successively.The structure and function of the lymphatic organs in E.tetradactylum have not been fully developed and maybe one of the main causes of high mortality during the metamorphosis period.This study is of great significance for optimizing breeding conditions,improving juvenile cultivation and healthy aquaculture technology.