Studies On Oviduct Structure Development Of Compound Eyes In The Embryonic And Larval Stages In Macrobrachium Nipponense

Macrobrachium nipponense (Crustacean, Decapoda, Caridea, Palaemonidea) is a kind of widely greeding freshwater shrimp in China. Oviduct is one of the main parts of the female reproductive system. In this research, the changes of the structure of the oviduct during spawning and the developments of the compound eyes in the embryonic and larval stages in M nipponense were studied with the methods of histological technology and transmission election microscopy.The structure of oviduct:1. Anatomy and histological structure. A pair of oviducts originates from the anterolateral part of the ovary, and ends at the female genital pores lying in the basipodite of the sixth thorax appendage. The oviduct wall consists of a thin layer of connective tissue, basal lamina and a layer of columnar epithelial cells. Before laying eggs, a lot of secretions appear in oviduct; epithelial cells show tightly each other; near the basal lamina, epithelial cells show finger-like protuberances; the layer of basal lamina is thin and there are another layer of connective tissue cells out of the basal lamina. After laying eggs, secretions disappear and epithelial cells die, but the histological structure of oviduct wall seems integrity.2. Ultrastructure. Two types of epithelial cells are found in oviduct wall, one with clear cytoplasm and the other with dark cytoplasm. The clear cells contain abound organelle compared with the dark cells. Near the oviduct cavity or near the basal lamina, epithelial cells show finger-like protubances.During spawning, the structure of oviduct is obviously affected. Before laying eggs, there are many secretions in oviduct and lots of microvilli at the surface of epithelial cells. The clear cells contain lots of mitochondria, endoplasmic reticulums and Golgi complexes. Two hours after laying eggs, the secretions disappear, and the surfaces of cellular membranes break in a sort, but most of the organelle retainintegrity and cellular inclusions appear in oviduct cavity. Three days later, cellular inclusions increase in oviduct cavity. Four to eight days after laying eggs, there are a lot of death cells in oviduct cavity and the renovation of epithelial cells become evident. Nine days later, microvilli of epithelial cell begin to increase, and secretions among mocrovilli also can be seen, and hi the cytoplasm the amount of organelle increases gradually. But comparied with that before laying eggs, the amount of microvilli, secretions, types and amount of organelle are few too. From fifteen days to eighteen days, a great deal of death cells can also be seen in oviduct cavity. In addition, eight days after laying eggs, it is found that cellular structures of oviduct near the female genital pores vary greater than those near the ovary during or after spawning eggs.3. After laying eggs, most of epithelial cells break and die, however, histologically, the structure of oviduct wall still remains normal. The reason should be relative to cellular junctions. Desmosomes appear between epithelial cells as the first junctions, and septate junctions widely exist between or among epithelial cells. It is believed that these junctions are important to remain the structure of oviduct and keep stable environment in vivo in Macrobrachium nipponense.4. Four different types of connective tissue cells are found out of the basal lamina, hi the first type of connective tissue cells, most of the nuclei are occupied by normal chromatins, but in other three types of connective tissue cells, abnormal chromatins are rich in nuclei. In addition, there are many small eletron dense granules in the second type of connective tissue cells and big eletron dense granules in the third type of connective tissue cells. The fourth types are stract cells, where endoplasmic reticulums showed concentric circle. It is found that the first, second and third types of connective tissue cells, which are analogous to crustacean haemocytes, are probably the originations of the renovation of epithelial cells.5. Virions in epithelia...