Studies On The Development Of Testis And Spermatozoa In Siniperca Kneri Garman

The two testes of Siniperca kneri Garman separate thoroughly in appearance. Each testis contains a main spermatic duct which locates in the cavity and runs lengthwise along the ventral side of the testis, connecting to the lumen of the testicular lobules. There is blood vehicle along the spermatic duct. The end of two spermatic ducts connect .. merge into the form of " Y" and go into the urogenital openning.Examined with a light microscope, the testis of sexually mature Siniperca kneri appears to have a lobular-type structure which are composed of several cysts and the testicular lobules distribute in radiation. The Sertoli cells envelop the germ cells forming spermatocysts which show characteristic synchronous development. The testis development stages are determined according to cell's morphological characteristics, its size and number and the varying extent of chromatic agglutination . The development of testis may be divided into five stages: (1)multiplication of spermatogonium; (2)growth of spermatocytes; (3) maturation of spermatocytes: (4) initial appearance of spermatozoa; (5) complete maturation of spermatozoa ?The reproductive seasons cover from March to April.The ultrastrutures of spermatogenesis and spermiogenesis of theSiniperca kneri (Garman) were investigated by means of transmission electron microscope. There are five developmental stages in the spermatogenesis, namely are primary spermatogonium , secondary spermatogonium , primary spermatocytes , secondaty spermatocytes and spermatids. The spermatids develop into sperm via the process of spermiogenesis. There exist cell junctions between two spermatids.The results reveal that there are two types of spermatogonium, primary spermatogonia (Sg1) and secondary spermatogonia (Sg2), in the early developmental stage of testes. During the stages of primary and secondary spermatogonium, components of the nucleolus, called chromatoid bodies(CB) , are excluded from the nucleus. As the cells differentiate from spermatogonium to spermatids, the number and size of CB gradually reduce and shrink. The CB in the cytoplasm usually locate near the nucleus. Sometimes a CB can be seen with most part in the cytoplasm and a small part in the nucleus. There are many CB that locate in the cytoplasm at the early stage which always associate with mitochondria. It is suggested that the components of the CB were ribosomes. Therefore many ribosomes produced by the primary and secondary spermatogonium may be used in the spermatogenesis. During the period of primary spermatocytes, we can observe the synaptonemal complexes(STC). The head of spermatozoa contains a nucleus but no acrosome. The nuclear fossa developes well. During the process of spermtogenesis, within the nucleus the chromatin condenses step by step into wads, among which are loose chromatin fibers. The centriolar complex, including the proximal centriole and the basal body, locates in the implantation fossa. The sleeve composes of several mitochondria and vesicles. The long tail stretches out of the central space of the sleeve. The principal components of the tail is axonemes which features a"9+2" pattern. There are vesicles outside the axonemes.The morphological feature of the somatic cells in the testis of Sinipercakneri, such as fibroblasts, Sertoli cell and Leydig cell are also described in the current paper, meanwhile, Both of Sertoli cell and Leydig cell possess some structural characteristics of typical endocrine gland cell and we have discussed their functions respectively.