Study On The Gonadal Development And External Sexual Characteristic Changes At Eary Stages In Neocaridina Denticulata Sinensis

Neocaridina denticulata sinensis belongs to Crustacea, Decapoda, Atyidae, Neocaridina.has many characters such as easy breeding and excellent reproductivity, so it’s a good materialfor ecological, physiological and toxicological experiments.Through histology, morphology and immunohistochemistry method,The embryodevelopment, the gonadal differentiated time and the germ cells’characteristics in gonadaldifferentiated process,change of external sexual characteristics of N. denticulata sinensis hasbeen investigated. This research would provide the basic data for reproductive biology andenvironmental biology research of N. denticulata sinensis. Further more, it has importanttheoretical and practical significance on crustacean’s reproductive and developmentalregulation and genetic breeding.1. Morphology study on embryo development of N. denticulata sinensisOne adult Females can take40-60eggs.The eggs are adhered at the basement of thefemale pleopods. External color changes took along with the vitellus’ degradation.Thehatching larva was similar to the adult.At the late stage of the embryo development,theeyes,heart,and segment were obvious. The connective position between funiculus and egg ofdenticulata sinensis is near the hepatopancreas.2. Histological study on embryo development of N. denticulata sinensisEmbryo of N. denticulata sinensis apply Discoidal to cleavage,it’s one of Meroblastictype. Blastomere invaginate to form gastrula. After gastrula embryo, different organs wereassembled by eloblast proliferation. Ectoderm differentiated into segment,appendage, foregutand hindgut.Mesoderm differentiated into blood vessel, nerve and muscle. Endodermdifferentiated into yolk endoderm,midgut and ancestor hepatopancreas.3. Immunolocalization of Nanos protein in N. denticulata sinensisN. denticulata sinensis Nanos protein was detected in the gastrula stage, located inventral edge of the embryo and connected to the yolk substance. At egg-nauplius stage, withthe development of embryos, these cells along the edge moved towards the embryo anterior.The movement is passively. Then germ cells migrated to the surface of the embryo,under the epidermis,gathered. Nanos protein synthesis was reduced, primordial germ cellsmigrate into the gonadal primordium at prehatching stage.4. Sex differentiation of early stages in N. denticulata sinensisThe ovogonium were forming and pretended between12and18days posthatch(dph).18-22dph was the critical time of the gonadal differentiation.there are two typegonadals were pretented in the period:type1and type2.Then the type1developed intoovarian and the type2developed into testis.The testis differentiation passed through aovotestis stage.In addition,the gonopods morphological changes in males were observed toprovide support to the early testis presence.5. Change of external sexual characteristics in N. denticulata sinensisN. denticulata sinensis mature male’s first pleopod endopodite is oval,no setae on it.There is eggs adered setae primordium at female first pleopod bending position and basementexclude the basement of others’pleopods. Male larvas at30days post hatch, appendix internaprimordium was appeared on the first pleopod endopodite. It’s grow slow-down but the firstpleopod endopodite outer edge growth and extension fast.The appendix masculine appearedmale larvas at30days post hatch, grew bigger than the appendix interna nearby gradually.Setae on the appendix interna degradated and gradually disappeared.