Ultrastructure And Immunohistochemistry Studies On Vitellogenesis In The Oocytes Of Neocaridina Denticulata Sinensis

At present,many scholars had done a devil of investigations on the ovary development and oogenesis of Decapoda crustacean. Nevertheless,it hadn't seen the reports correlated vitellogenesis in the oocytes of Neocaridina denticulata sinensis.The study on the regulation mechanisms of reproductive development in N. denticulata sinensis was not very clear. Transmission electron microscope (TEM) and immunohistochemistry were employed to research the morphologic change characteristics of various kinds of organelles in oocytes and the structure changes on follicular cells during the vitellogenesis of N. denticulata sinensis systemly. This research would provid further rationale for studing the vitellogenesis of crustacean.It possessed significant practical purpose on reproductive development regulation and breeding in crustacean.It also would be the theory guide on using the vitellogenin as Environmental Endocrine-Disrupting Chemicals'biological marker in toxicology further research.This research provided a good kind of study subject for toxicology as well.The N. denticulata sinensis's ovary is divided into the anterior lobe and posterior lobe. The anterior lobe joins together and locates between the heart and hepatopancreas. The posterior lobe locates above the intestinal tract and parallels with it. During the development of ovary, we could observe the oocytes during different phases.The ovogonium:the cell was spherical. The volume was comparatively small. The nuclear-cytoplasmic ratio was large.The cytoplasm was well-distributed.All of cells disposed tightly fairly.The prophase of vitellogenesis:the volume grew. The cytoplasm still remained well-distributed.The follicular cells appeared in this phase. But the amount was very low.The distribution of follicular cells was quite irregularity. They had a tendency to surrounding and dividing the oocytes by degrees.The earlier period of vitellogenesis:the synthesis activity of vitellogenin started overall. The corpuscular volume was go on growing.The oocytes'cytoplasm began to appear yolk sphere.The oocytes were entirely surrounded by multilayer follicular cells.But the relation was loosing.The metaphase of vitellogenesis:the corpuscular volume continued growing.The shape of oocytes was irregularity gradually and approximating a triangle. The oocytes were completely divided by unilaminar follicle cell.The follicular cells stuck to the oocytes tightly. The anaphase of vitellogenesis:the oocytes were filled with vitellus material.A part of oocyte's nucleus even disappeared.The follicular cells started to degenerate and deflated.The maturation phase:The oocytes were full of ripe vitellogenin. The follicular cells became a extreme tenuis wrap and even vanished.Our observation was carried out on these base by transmission electron microscope. The results indicated a dual origin of the yolk. All kinds of organelles were involved in endogenous yolk formation during the vitellogenesis period,for example:mitochondria, endoplasmic reticula, lysosomes and ribosomes.The mitochondria were the first organelles involved in yolk granules formation. However, the endoplasmic reticula were the dominant organelles which played the most important role in the metaphase and anaphase of vitellogenic oocytes and then developed into the bigger yolk granules with membranes. Furthermore,the lysosomes played the typical function in the same phase.They engulfed and resolved the mitochondria and endoplasmic reticula to expand the yolk sphere's volume, at last formed high electron-dense yolk granules. Exogenous yolk formation was carried out primarily by microvillus and pinocytotic vesicles of the plasma membrane which uptook the exogenous materials from the perivitelline space or follicular cells.The results of immunohistochemistry research would be an important test and supplementary to the above-mentioned resultant.The research discoverd by analyzing that the oocytes' cytoplasm were the major arena of endogenous yolk formation during the vitellogenesis period.In the prophase of vitellogenesis,the amount of vitellus material was very low.During the vitellogenesis period,the vitellus material accumulated quickly. In addition,there were vitellogenin in follicular cells.The result would be a further proof to certificate that follicular cells were the major arena of exogenous yolk formation in N. denticulata sinensis. Simultaneously,it also confirmed the conclusion of a dual origin of the yolk.