| 1 Observation on embryonic life history of Eleutheronema tetradactylumObservation on embryonic development of E.tetradactylum was studied in this paper. Zygotes fertilized naturally obtained from those 2 years old cultured E.tetradactylum with the processing of natural spawning. The result showed that mature zygote of E.tetradactylum was round with a oil ball in the center, the average diameter of zygote was 675.78μm, and the oil ball average diameter was 258.46μm. The embryonic development finished in 13 h 52 min under 31~33℃ at salinity 27.50~28 and pH8.2. The process of embryonic development was fast which could be divided in to 6 stages, including cell division stage、blastula stage、gastrula stage、embryo development stage、organs differentiation stage and hatching stage. Body length of newly hatched larvae was 1.46±0.25 mm, while 3DAH larvae is 2.42±0.18 mm with the mouth and anal opening, being able to feeding initiatively。 2 Tolerance on different salinity of fertilized egg and larval of E.tetradactylumThis study was conducted to investigate the effects of different salinity on the sinking,buoyancy,hatching and abnormal rate of fertilized egg of E. tetradactylum, salinity gradient of 5, 7, 9, 11, 13, 15, 20, 25, 28(as control), 30, 35, 40, 45 were setting, furthermore, the survival activity index(SAI) of larval E.tetradactylum was observed. The results showed that both fertilized eggs in the stage before the first division and the gastrula were in sink at salinity below 25, suspending in the central layer when salinity was 25, and in buoyancy at salinity up to or above 28. Fertilized eggs before the first divisions were more sensitive to salinity changing than those in the gastrula stage. Survival rate and SAI value of newly hatched larvae were impacted deeply by salinity change. Based on hatching rate, abnormal rate of larval and SAI value analysis, It speculate that the suitable salinity range of E.tetradactylum fertilized egg hatching is 25 ~ 35, the optimum value is 35. 3 Histology observation in digestive tract of E.tetradactylum compared in different development stagesThis work aimed to figure out constructional differences of the digest tract in E.tetradactyl belonging to different development stages and the technology of conventional paraffin section and HE staining was using. Result shows that, we find that the digestive tube has not been differentiation with only intestinal tube of clining to the abdominal wall and the yolk sac in 1 DAH larvae under the condition of water 29~32℃,salinity 25~28, dissolved oxygen 4.80~5.5 mg/L,pH 8.0~8.3. Larvae begun feeding, and digestive tube also communicates with the outside world when the yolk sac absorbed completely in 3 DAH, indicating the larvae could maintain its own growth with the ability of digestion and absorption independently to some extend, made it changing from endogenous stage nutrition to exogenous feeding gradually with the differentiation of esophagus、stomach and intestine.Gastric gland and pyloric caecum occurred in 15 DAH, this issue was the symbol of developing to juvenile stage. Digestive tract developed enough structurally and functionally, which would greatly enhance its capacity for digestion. The structure of digest tract in 30 ~ 35 DAH was differentiating functional similar to young and adult fish. Conventionally, the pipe wall composts of mucosal、submucosal, muscular layer and the serosa. The number of mucosal fold、gastric gland and goblet cell in the epithelium mucosal is showing an increasing regularity among juvenile, young fish and adult fish, indicating that the digestive tract develops gradually in structure and funtion. Based on the development characteristics of digestive system, we discuss the three major crises in the process of seedling and corresponding measures are putting forward. 4 A Comparative Histochemical Study on Mucous Cells in Digestive Tract of E.tetradactylum with larvae, juvenile, young Fish and Adult FishHistochemical properties of mucous cells in digestive tract of E.tetradactylum juvenile、young fish and adult fish were studied and technology of AB-PAS(Alician blue and periodic acid Schiff reagent, Alician blue at pH 2.5) staining was used. The results showed that the mucous cell first occurred in esophagus in 5DAH larvae, which was classified as typeⅡ, and the number of this cell was increasing at 9DAH, in which the stomach was distinguished as “Y” containing cardiac stomach、pyloric stomach、fundic stomach and gastric caeca with mucosal coat covering the surface where a large number ofⅠtype mucous cell were found. Type Ⅱ mucous cell was detested out in gastric area and the intestine of 15 DAH larvae. Mucous cell first appeared in pyloric caeca of 17 DAH larvae was type Ⅱ. No new types of mucous cell were found out in 23 and 30 DAH larvae but the density was increasing regularly. There display a little bit Ⅰtype mucous cell while much Ⅱtype mucous cell in the esophagus of 35 DAH;Ⅰtype and Ⅲ type mucous cells can be detected in foregut, the former seems to be much in number than the latter. There are only Ⅱtype mucous cell detected in midgut and hindgut, while no mucous cell is figured out in pyloric caeca. It can be described as a mounts of mucous cells exposing in the digestive tract of 65-day-old juvenile. There are Ⅰ, Ⅱ, Ⅲ, Ⅳ type mucous cells in esophagus and foregut. Density of mucous cells in esophagus has the highest value followed by hindgut, while mucous cells in other sections characterize as having at least two types and rich in number.Though types of mucous cells are not rich as those in 65 DAH young fish, but the number of mucous cells is increasing extremely in adult fish. There are mounts of Ⅱ and Ⅳtype mucous cells distributing in esophagus, while mucous cells of pyloric caece are characterized as with the same types as esophagus, but not rich in number. Mounts of Ⅰ types mucous cells expose in mucosal epithelium of stomach and quiet a lot of Ⅳ type mucous cells are being tested in gastric gland of stomach. Ⅲ and Ⅳ types of mucous cells in intestine can be distinguished as numerous、various in shape and big in size,and the density of mucous cells in foregut, midgut, hindgut showing an increasing regularity. The result indicates that mucous cells development in E.tetradactylum of different development stages is improving from immature style to mature style. |
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