Studies On The Shell Characters, Feeding And Digestive Systems And Nuclear Dna Of Saxidomus Purpuratus (sowerby)

In this paper,the influence of shell characters on live body weight,gill,mantle, labial palp,digestive system and DNA contents of Saxidomus purpuratus (Sowerby) are studied by biostatistics,histology,scanning electron microscopy and flow cytometry.This study is focus on Saxidomus purpuratus (Sowerby) at three years old from sea area of Dalian City.The shell length(X1),the shell width(X2),the shell height(X3) and the live body weight(Y) are measured.The influence of those shell characters on live body weight is quantitatively analyzed by correlation analysis, path analysis and regression analysis,and regression equation is obtained.The results show that the live body weight is significantly and positively correlated with preceding three shell characters.Shell width gives most direct effect on the live body weight,which is the key influencing factor.Shell height gives significant indirect effect on the live body weight.There is accordant mutative trend between the results of determinant coefficient analysis and path analysis.The multiple regression equation obtained to estimate live body weight asY=-390.8778+24.9149X1+45.7710X2+18.0784X3.In selective breeding of Saxidomus purpuratus,the shell length,the shell width and the shell height are perfect measuring indexs.The histological and surface structures of the gill of Saxidomus purpuratus are observed by means of optical and scanning electron microscopes.Saxidomus purpuratus has two pairs of lamina, and each of which is composed of the inner and outer lamellae. Every lamella consists of many longitudinal-arranged gill filaments. The gill filaments can not be divided into main filaments and ordinary filaments. The structure of the gill contains the epithelium and the blood cavity under epithelium.According to the structure and function,the epithelium of gill filament is seperated into columnar cells and flat cells.The frontal cilia and the lateral cilia on the surface of the columnar cells are related to carrying food particles and generating water current respectively.The flat cells are respiratory epithelia,whose histological and surface structure fits for gas exchange.About 22~30 filaments are joined into a bunch,which formed an obvious raise on the outer surface of the lamina.Neighbouring filaments are linked together by interfilament junctions containing blood vessel .Two lamellae are also connected by lamellae junctions in which contain blood vessel.The mantle of Saxidomus purpuratus is studied by histology and scanning electron microscopy.The mantle of Saxidomus purpuratus extends from the backside to the abdomen of the limp body,inclosing visceral mass and gill and so on.The left and right mantle do not scar over completely,but be evolved to the entering and exporting water pipes in the back-end.The mantle belongs to trifora.It can divide the mantle into the middle zone and the marginal zone in terms of adhesion point.The marginal zone is thicker than the middle zone.The latter is translucency.There is something diversity about the different part of the mantle in shape,but the histological structure of that is similar.It is composed of inner epithelium,outer epithelium,connective tissue, muscular fiber and secreting cells.Observing throught scanning electron microscope, the surfaces of inner and outer epithelium are not evidently streaky.There are cilia clusters and numerous secretory vacuoles on the surface of the inner epithelium.The surface of the outer epithelium also has numerous secretory vacuoles,but not cilia.The histological and surface structures of the labial palps of Saxidomus purpuratus are observed by means of optical and scanning electron microscopes.The labial palps are located in the front of the body and similar in form a triangle.There are two pairs of labial palps that are the inner one and the outer one,which has a ridged surface and a smooth surface.The labial palps are jointed in the bottom to form the mouth.The labial palps are composed of inner epithelium,outer epithelium,connec- tive tissue containing blood cavity and muscular fiber.The ridges and grooves of the ridged sueface have dense cilia.There is fewer cilia on the smooth surface.It is similar in a cluster and it is shorter than that of the ridged surface.There are a great many mucous cells forming many spherical granules on the smooth surface of the labial palps.The cilia and grume play important roles in choosing food particles and delivering food to the mouth.The digestive system is studied in Saxidomus purpuratus by histology.The result shows that the digestive system is composed of digestive pipe and digestive gland.Digestive pipe is a slender tube from the mouth to the anus,followed by mouth,esophagus,stomach, intestine,rectum and anus.Normally,from the inner to outer,the tube is composed of mucosa,submucosa and serosa,not muscular coats.Submucosa and serosa are formed of connective tissue which is rich in blood lacunar.The mucosa epithelium has cilia and mucous cells that in food transport play an important role.The structure of mouth is very simple.Stomach shows an irregular pocket and contains crystalline style.Intestinal wall create many sizes of fold,to increase the absorption area.Digestive gland is a structure of epithelial differentiation and is a compound tubular gland.The digestive gland is main hepatopancreas.There are two kinds of cells in digestive gland which are digestive cells and basophilic cells.The digestive gland is made of many small tubes with branches.There is a little connective tissue among these tubes.The nuclear DNA contents of Saxidomus purpuratus(Sowerby) is tested by flow cytometry.The result shows that the mean value of the nuclear DNA contents is 3.2357±0.0321pg.There is not remarkable diversity among the having been measured Saxidomus purpuratus through One-Way ANOVA.