PATHOLOGICAL CHANGES OF SHUI-BIE-ZI DISEASED CHINESE MITTEN CRAB ERIOCHEIR SINENSIS IN THE DIFFERENT STAGES OF DISEASE

The pathological changes of " shui-bie-zi” diseased Chinese mitten crab Eriocheir sinensis were analyzed in order to understand the process of disease occurrence and development and reveal the nature of disease. According to hepatopancreatic colours of the diseased crabs, the disease was divided into four stages of light yellow, light pink, milky white and grey respectively. The results showed that as the development of the disease, the weight ratio of hepa-topancreas with crab body reduced gradually, and the weight ratio of haemolymph in the cavity with crab body and the diameter of hepatopancreatic tube decreased gradually. These indexes of diseased crabs in four stages of disease were extremely significant difference compared to healthy crabs respectively (P<0.01). Except there were no significant differences of the weight ratios of hepatopancreas with crab body between the milky white stage and the grey stage, and of haemolymph in the cavity with crab body between the light pink stage and the milky white stage and between the milky white stage and the grey stage, and of the diameter of hepatopancreatic tubes between the milky white stage and the grey stage (P>0.05) and there was significant difference of the diameter of hepatopancreatic tubes between the light pink stage and the milky white stage (P<0.05), these indexes were extremely significant differences between the other various stages of diseased crabs (P<0.01). The histopathological changes of hepatopancreas, gill, muscle and cardiac muscle were similar among six kinds of tissues or organs of diseased crabs in the four stages of disease. The main histopathological changes of hepatopancreas, gill, muscle and cardiac muscle were edema and atrophy in the light yellow stage. Edema and atrophy are reversible histopathological processes. Necrosis of hepatopancreas and muscle appeared in the light pink stage and was more serious in the later stages. Necrosis of gills and cardiac tissue appeared in the milky white stage and the grey stage. Necrosis is an irreversible histopathological process. Histopathological changes of nerve and intestinal tract were not obvious. According to the histopathological characteristics in the different stages, diseased crabs could recover only in the light yellow stage by eliminating the cause which will be determined in the future. Diseased crabs are impossible to recover due to the necrosis of major organs or tissues in the light pink stage and the later stages even the cause of disease is eliminated. Diseased crabs should be cleared away in time in order to reduce the economic losses of further breeding.