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Important decisive factor in the development of embryos and larvae of marine shellfish in seawater, the hemolymph defense mechanism has not yet formed, or the beginning of happen, chemical defense and molecular protection system is to ensure that the early development stages of the marine shellfish can survive . Survival factor, especially early developmental stages affect marine shellfish-depth understanding of the chemical factors, helps to take measures to prevent the occurrence of disease in our in economic shellfish artificial breeding process, improve the survival rate of the spat. In this paper, eggs, embryos and early larvae esterase (Esterase EST) Histochemical and spectrophotometric techniques mussels (Mytilus edulis) peroxidase (Peroxidase POD), acid phosphatase (Acid phosphatase, ACP) and alkali phosphatase (Alkaline phosphatase, AKP) activity positioning and quantitative research to explore the the shellfish during early development in the immune defense mechanism. The results show that the EST, POD, ACP and AKP were present in the mussel oocytes, embryos and larvae, but the distribution and content in various developmental stages. Histochemical various developmental stages from the oocyte to the D-type veliger embryos and larvae showed EST strong positive and POD positive; oocytes area larger and lighter in color; morula stage started in different cells positive strength difference; gastrula, trochophore and D-veliger cells positive strength differences gradually increase. Histochemical from egg to various periods of the D-type veliger were tested ACP and AKP positive egg positive particles larger and more evenly distributed, the fertilized egg coloring darker central the cleavage stage nuclear area was strongly positive and the Great Schism positive particles inside the ball more, stronger the gastrulation and Trochophore outer layer of cells positive, veliger mantle edge of the membrane, the visceral mass and the base of the face plate was strongly positive. The spectrophotometric measurement results show that α-acetate esterase activity increased slightly, the lowest in the oocytes, zygotes, cleavage stage embryos to improve peaked, blastula, gastrula and trochophore decreased, veliger of the D-type decline. α-butyrate esterase activity, oocytes fertilized egg slightly higher peaked cleavage stage embryos to D-type veliger period of gradual decline, the lowest D-type veliger. Does not depend on the halogen-POD activity the lowest egg fertilized egg peaked raise larger, blastula, gastrula, trochophore and D-veliger gradually reduced. Dependent halogen POD activity does not depend on the halogen POD activity were similar, but the fertilized egg to raise smaller, while the cleavage stage to improve. Biochemical determination of ACP and AKP vitality, are egg minimum gradually increase as the development of enzyme activity, which the ACP vitality improved significantly after fertilization and blastocyst stage, blastula peaked and then declined slightly; AKP activity in the cleavage stage trochophore and veliger improve larger, veliger stage the highest enzyme activity. EST, POD, ACP and AKP were part from the mother and fertilized role in promoting the production of enzymes. EST, POD, ACP and AKP pathogen infection may play an important role in the early development of the mussel resistance.
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