Study On Annual Change Of The Testicular Development And Spermatozoa Into Eggs For Pseudobagrus Ussuriensis

Pseudobagrus ussuriensis is a kind of important economic fish,which taste delicious and has high nutritional value.Development of testes,the fine structure of the spermatozoon and spermatozoa into eggs were studied in order to provide reference for increase of fertility rate and artificial breeding.The structure and annual changes of development of Pseudobagrus ussuriensis testis were studied by paraffin slice and histological staining techniques.The spermary of Pseudobagrus ussuriensis of lobular type.The non-germinal cells,both leydig and Sertoli cells,were observed in testes of Pseudobagrus ussuriensis.The testis development at the age of sex maturity could be divided into the following stages:(1)the recovery stage(â…¢);(2)the spermiogenesis stage(â…£);(3) the maturity stage(â…¤);(4)the stage after spawning(â…¥).It begins spermatogenesis in April.Its reproductive period is from June to July,stageâ…¥is f rom September to October and stageâ…¢is f rom November to late March.Observed the fine structure of the spermatozoon of teleost Pseudobagrus ussuriensis using transmission electron microscope.The spermatozoon of Pseudobagrus ussuriensis consists of head, middle piece and tail.The head is like a globe or an ellipsoid.There is no acrosome at the anterior end of the nucleus,whereas there is an implantation fossa at the posterior end of the nucleus,within which the chromatin is dense and nuclear vacuole(NV)is existent.The middle piece consists of the centriolar complex and the sleeve.The implantation fossa of spermatozoon of Pseudobagrus ussuriensis sink into cell nucleus in the back of cell nucleus,exceeding 1/2 of the cell nucleus long, the major axis of its and cell nucleus is parallel.The centriolar complex is in the implantation fossa,which consists of proximal centriole,intercentriolar body and basal body.The proximal centriole is in the front of the implantation fossa,the basal body is in the middle of the implantation fossa,the proximal centriole and the basal body are arranged in a line.The intercentriolar body is located between the proximal centriole and the basal body and is perpendicular to them.The sleeve,which is rich in mitochondria,is connected to the posterior end of the nucleus.The main structure of the tail is axoneme,which is the structure of a typical"9+2".Two sides outside the axoneme for symmetry fin kind structure that the cytoplasm become.There are no vesicles nor other cell organelles in the tail.The mature eggs and fertilization process were observed by scanning electron microscopy in Pseudobagrus ussuriensis.The mature eggs of Pseudobagrus ussuriensis are elliptical and have a single micropyle on the animal pole,from which there are 30 to 40 fossae and ridges radiating from the egg surface.The micropyle is exposed before insemination,spermatozoon was found at 2s after insemination.Soon after that,numerous spermatozoa adhere on fibroid slipcover.The fibroid slipcover disappeares and the micropyle is exposed at 10s.The process of sperm penetration into eggs is carried out between 10s and 1min and a circle of annular apophysis encircles the micropyle on the egg membrane.Only few spermatozoa can go through the apophysis and reach the vestibule of micropyle.The tail of spermatozoa around the micropylar is disorganized at 1.5min after insemination and the head is disrupted at 5min.During this period,the annular apophysis disappears soon after two circles form and fertilization plugs appear,resulting in the block of sperm penetration.Almost all of the spermatozoa on the micropylar region are dissolved in 20 min.