草鱼胸腺组织学的研究

草鱼胸腺位于鳃腔背上角,紧贴在鳃腔膜之下,突起部分伸入到下颞凹,整个胸腺形态形似菱角。其组织结构可分为外区、中区和内区。中区和内区主要由淋巴细胞和网状上皮细胞构成,在组织结构上分别类似于高等脊椎动物胸腺的皮质和髓质区。胸腺淋巴细胞可分大、中、小三型,小淋巴细胞约占78％,中淋巴细胞约占15％,大淋巴细胞约占4％。在Ⅰ龄草鱼,每毫克胸腺约有3.6×106个胸腺淋巴细胞,Ⅱ龄草鱼约为2×106。Ⅰ至Ⅱ龄草鱼胸腺重量明显地随鱼龄增加,Ⅱ龄以上草鱼胸腺重量变化无规律,成鱼胸腺表现出明显的退化。草鱼胸腺除年龄性退化外,还存在环境因素引起的非年龄性退化。  

STUDIES ON THE HISTOLOGY OF THYMUS OF THE GRASS CARP

The thymus of grass carp is situated on either side of the upper corner of the opercular cavity. It lies closely under the membrance of the opercular cavity. The projecting part of the thymus is protracted into the subtemporal hollow. The shape of the total thymus is similar to that of water chestnut. The thymus of grass carp consists of the outer, middle, and inner regions. The middle and inner regions consist chiefly of lymphocytes and reticuloepithelial cells, whose structural features are similar to those of the cortex and medullary region of the higher vertebrates respectively. There is no abvious demarcation between middle and inner regions. There are three types of lymphocytes in thpmus: large (4%), medium (18%) and small lymphocytes (78%). The number of thymus lymphocytes is approximately 3.6?06 cells per milligram in oneyear-old fish, and 2?06 cells per mg in two-year-old grass carp. In one and two year old grass carp total weight of the thymus increased with age, but in bigger fish thymus weight does not change in a regular way. Adult fish show apparent degeneration in thymus. The thymus of grass carp also shows age-independent degeneration caused by nutritional and enviromental factors.