OBSERVATION ON THE DEVELOPMENT OF THE LATERAL LINE NEUROMAST OF SIBERIAN STURGEON(ACIPENSER BAERII)

Acipenseriformes fish is a kind of the ancient chondrichthyes fish,and Siberian sturgeon(Acipenser baerii) plays an important part in the evolutionary history of vertebrates.Lateral line neuromast is the key part of the lateral line system-a very important sense organ of fish.Therefore,it is necessary to pay attention to the development of the lat-eral line neuromast of the Siberian sturgeon.In order to observing the morphology and tracking the development of lateral line neuromast of the Siberian sturgeon larvae in the different development periods after hatching.The 5μm of the paraffin sections of the adult fish of the Siberian sturgeon were prepared and then stained with HE.Meanwhile,the Siberian sturgeon larvae in different periods after hatching stained with 10μmol/L DiA [4-(4-Diethylaminostyryl)-1-methylpyridinium iodide] which can be used as the neuromast specific markers.The results showed morphology of the neuromast in the lateral line canal: The hair cells erected and arranged closely.Compared to Hammerhead shark(Sphyma lewini),Japanese eel(Lyncozymba nystromi) and Tongue sole(Cynoglossus semilaevis),all of these species had many common characteristics: The neuromast included epithelial cells,hair cells and supporting cells.However,each of these species had special characteristics: The Siberian sturgeon had smaller amount of the hair cells;the Ham-merhead shark had larger amount of the epithelial cells;the Japanese eel had many vacuoles in the supporting cells and the neuromast of the Tongue sole exposed to the skin surface.At the same time,the development of the lateral line neuromast of the Siberian sturgeon had been tracked: 3 days after hatching,the ganglia had dramatic differentiation and development in the region of the ear;10 days after hatching,the ganglia in the region of the ear had differentiation and formed lateral line neuromast above and below the orbital and also began formatting the lateral line neuromast on the opercular;15 days after hatching,the lateral line neuromast above and below the orbital became more obvious,and the lateral line neuromast on the trunk had basically developed;Finally,it is observed that the lateral line neuromast of the Siberian sturgeon larvae had developed completely in 22 days after hatching.Compared to Zebrafish(Danio rerio) and Catshark(Scyliorhinuscanicula),the development process of the lateral line neuromast of all these species were nearly the same.This study may lay morphologic foundation for the further researching on the related genes which express in the development of the lateral line neuromast of the Siberian sturgeon as well as provide useful information for the fur-ther studying on the migration of cells in the development of the lateral line neuromast of the Siberian sturgeon.