Reproductive Biology And Fertilization Research On Apostichopus Japonicus

Reproduction of Apostichopus japonicus was investigated by morphological and historical examination ; we use scanning electronic microscope (SEM ) and transmission electronic microscope (TEM ) to study the gametogenesis of Apostichopus japonicus and summarize its specialty. the progress of fertilization of Apostichopus japonicus was studied by normal and fluorescence microscope, SEM, TEM. We expect this research would offer some cytological information and referenced theoretics. The main content is composed of 4 parts as follows:1. Morphological and historical observation of the gonad development of Apostichopus japonicusAccording to the morphological and historical characteristics of the gonad of Apostichopus japonicus,the progress is divided into 4 phases: recovery; growth; mature; spawned. The length and diameter of tubules increase from March, the color is deeper and the number of branches increases, reaching its peak during mature phase. The length and diameter of tubules decrease after spawning while the thickness of gonad wall undergo an opposite way, Apostichopus japonicus has a annual reproductive pattern, spawning occurs during the middle of April and late May. Severity happens in the middle of May. Apostichopus japonicus may spawn several times during its breeding season.2. Ultrastructural Studies on Spermatogenesis of sea cucumber Apostichopus japonicusThe ultrastructure and development of sea cucumber (Apostichopus japonicus) was observed by the electron microscope, spermatogonium has a distinct nucleolus,and some proacrosomal granules, chromatin condensation is fond to be started during primary spermatocyte phase,the tail emerges in the following stage.in spermatid phase , proacrosomal vesicle was formed and will gradually developes into an acrosome, Mitochondria gradually fuse and increase in size,providing energy for sperm's movement. Mature spermatozoon belongs to primitive type ,consisting of head , middle piece and tail . The acrosome in the head is spheral in shape, there is only one mitochondria in the mature sperm .The flagellum has a simply"9 +2"microtubular structure.3. Ultrastructures of Apostichopus japonicus during oogenesisUltrastructural changes of Apostichopus japonicus was observed under TEM, the result indicated that the oogenesis of Apostichopus japonicus can be divided into 4 phases: oogonium; early vitellogenic oocyte; mid vitellogenic oocyte and end...