| Glyptosternum maculatum, one species of Glyptosternoids, is distributed in the mid-reaches of Yarlung Zangbo River as well as its tributaries in the Tibetan Plateau of China. G. maculatum belongs to the genus Glyptosternum (McClelland), the family Sisoridae, in the order Siluriformes. Besides the celiac liver, there is another structure called "exo-celiac liver" located between skin and muscular layer, and connected with the celiac liver by a funiform tissue, "joint belt". According to previous research, "exo-celiac liver" has been proven to be a unique normal tissue in G. maculatum. This dissertation studied the liver morphogenesis of the yolk-sac larvae, the physiological and biochemical differences between celiac liver and exo-celiac liver, the liver characteristics of sisorid catfishes, and the haematology. The main results are shown as follows:1. The location of the liver in G. maculatum first appeared in the left side of primary alimentary tract. The liver morphogenesis was divided into three phases:(1) no exo-celiac liver, (2) appearance of the "protrusion", and (3) appearance of exo-celiac liver. The exo-celiac liver progressively forms as the adjacent tissues grow larger (muscle of parietal peritoneum thickens, the size of bony bladder and oesophagus is enlarged). Exo-celiac liver located in the abdominal cavity just as celiac liver, so we considered that'exo-celiac liver'should be instead of'attaching liver', and the'celiac liver'should be instead of 'main liver'accordingly.2. The microstructure and ultrastructure of main liver and attaching liver were similar in G. maculatum. In histology, joint belt as the connecting bond of material transport between main liver and attaching liver, its vein, artery and bile duct were larger than both of them.3. We determined the contents of biochemical compositions, enzyme activities and total antioxidant capacity of main liver and attaching liver in G. maculatum. The contents of protein and lipid, total antioxidant capacity, activities of SOD and CAT in main liver were all slightly higher than those in attaching liver. The content of glycogen, activities of LDH, ALT and AST were all lower than those in attaching liver. However, there were no significant differences in all parameters between main liver and attaching liver (P>0.05).4. We obtained the specific sequences ofβ-actin,Cu-Zn SOD,Mn SOD and CAT, and determined the relative gene expression of Cu-Zn SOD, Mn SOD and CAT in main liver and attaching liver of G. maculatum by fluorescence quantitative PCR with P-actin as a control. The relative mRNA levels of Cu-Zn SOD, Mn SOD and CAT in main liver were significant higher than those in attaching liver (P< 0.05).5. Eighteen species (10 genera) of sisorid catfishes were dissected in this research,7 species of which possessed obvious attaching liver, whereas the other 11 species (4 genera) had no attaching liver. The differences of hepatic morphology occurred among different genera. The glyptosternoid fishes possessed attaching liver, whereas Bagarius, Gagata, and Glypothorax had no attaching liver. The hepatic heteromorphosis appeared in different species whthin the same genera. Pseudecheneis sulcatus possessed attaching liver, whereas Pseudecheneis intermedius had no attaching liver. The order of the weight ratio of attaching liver to main liver is P. sulcatus, Pseudexostoma< Pseudexostoma< Euchiloglanis< Glyptosternum< Exostoma< Glaridoglanis.6. The correlation analysis of the tracks of different groups and elevation of Chinese sisorids (significantly positive correlation) showed that as the elevation became higher, the hepatic characteristics of sisorids had a trend as follows:no attaching liver (Bagarius and Gagata)→appearance of the hepatic protrusion(Glypothorax)→evident protrusion (Pseudecheneis intermedius)→appearance of attaching liver (Pseudecheneis sulcatus)→larger attaching liver (Glyptosternini fishes). Attaching liver formed as the body forms of sisorids changing in the process of adapting themselves to the environment of high elevation and torrent stream, which is an acclimation to particular environment.7. Based on the relative size of attaching liver from small to large, the phylogeny of the glyptosternoid fishes in this research presented the following tendency of evolution: Pseudexostoma (attaching liver is obviously smaller than main liver)→Pareuchiloglanis (attaching liver is smaller than main liver, but larger than Pseudexostoma)→Euchiloglanis (attaching liver is smaller than main liver, but larger than Pareuchiloglanis)→Glyptosternum (attaching liver is smaller than main liver, but larger than Euchiloglanis)→Exostoma (attaching liver is similar to main liver)→Glaridoglanis (attaching liver is larger than main liver).8. Red blood cell count (RBC), haemoglobin concentration (Hb), haematocrit (Hct), crythrocyte osmotic fragility (maxEof and minEof), the erythrocyte sedimentation rate (ESR), mean cell volume (MCV), mean cellular haemoglobin content (MCH), and mean cell haemoglobin concentration (MCHC) were determined. Compared with other Siluriformes fishes, G. maculatum showed similar mean values for Hct, Hb, MCH, and MCHC and had slightly lower RBC and higher MCV. Alanine aminotransferase, aspartate aminotransferase (AST), alkaline phosphatase, total protein, albumin, globulin, albumin/globulin ratio, total bilirubin, direct bilirubin, urea, creatinine, glucose, total cholesterol, and triglyceride were assayed. The result showed that the value of AST in G. maculatum was obviously higher than that in other Siluriformes fishes.9. The peripheral blood cells of a sisorid catfish G. maculatum were studied by light microscope and transmission electron microscope. Erythrocytes and five types of leucocytes:lymphocytes, heterophils, monocytes, thrombocytes, and plasma cell were characterized in G.maculatum blood. The morphology and structure of blood cells of G. maculatum were basically similar to those of other Siluriformes fish species, although there were also main differences, such as larger erythrocytes than other catfishes, absence of basophils and acidophils, and various types of thrombocytes (five types:lone nucleus, fusiform, tadpole-like, oval, and in a cluster).
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