| 摘要: |
| 于1988年4月–1990年6月，在实验室培育锯缘青蟹幼体，从蚤状幼体Ⅰ期培养至仔蟹期。固定各期幼体，通过组织学切片和透射电镜观察研究锯缘青蟹幼体的肝胰腺。结果表明，锯缘青蟹幼体的肝胰腺由四种类型的细胞组成，这四种类型的细胞分别为：胚细胞（E－细胞）、纤维细胞（F－细胞）、吸收细胞（R－细胞）和分泌细胞（B－细胞）。不同类型的细胞显微和超微结构具有明显不同。E－细胞的细胞器不发达；F－细胞内含丰富的粗面内质网，且细胞质中可见酶原颗粒；R－细胞线粒体和滑面内质网比较丰富，呈明显的极性分布；B－细胞内含一个大的液泡，顶端存在顶端复合体，在B－细胞内可观察到胞引作用和胞内消化现象。根据对肝胰腺显微和超微结构的观察提出锯缘青蟹幼体肝胰腺细胞的分化序列，即E－细胞分化有两个趋向，一部分分化为F－细胞，由F－细胞转化为B－细胞；另一部分分化为R－细胞，R－细胞最终发生退化。 |
| 关键词: 锯缘青蟹幼体 肝胰腺 显微结构 超微结构 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金资助项目，3870497号 |
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| STUDIES ON THE HEPATOPANCREAS OF LARVAL SCYLLA SERRATA |
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LI Fu-hua,LI Shao-jing
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1.Institute of Oceanology, The Chinese Academy of Sciences, Qingdao, 266071;2.Department of Oceanology, Xiamen University, Xiamen, 361005
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| Abstract: |
| Larval Scylla serrata were cultured from the first stage of zoea to the first larval crab in every April from 1988 to 1990. For every stage, larval Scylla serrata were fixed in Bouin's fluid and 2.5% glutaraldehyde separately and their hepatopancreas were studied using light and transmission microscopes. The result obtained through histological sections shows that the hepatopancreas of larval Scylla serrata of many blind tubules. With the development of larval stages, the length and amount of hepatopancreas tubules increase. The hepatopancreas cells can be divided into four types: embryo cells (E-cells), fibrillar cells (F-cells), resorptive cells (R-cells) and blister-like cells or secretary cells (B-cells) (Plate I:1). These types locate at one thin basophile basement. Connective tissue, blood sinus and a lot of dissociate cells fill among the hepatopancreas tubules. The whole hepatopancreas is covered by a basophile membrane (Plate I:1). E-cells locate at the blind end of tubules. A round or oval nucleus exists in E-cells. E-cells at the mitotic division state can be observed sometimes; they may be involved in mitotic activity for production of other cell types which comprise the tubule epithelium. Bytoplasmic organelles are undeveloped. The mitochondria with little ridges appears as small spheres or rods. High amounts of rough endoplasmic reticulum (RER) exist in E-cells. Little lipid droplets and Golgi bodies were observed once (Plate I:2). F-cells mainly locate in the middle region of the tubules, scattering among R-cells and B-cells. It is strongly basophile. Plenty of RER can be observed in F-cells. The number of RER and electron density of mitochondria differ in F-cells located at different positions of the tubules. Golgi bodies are very rich in F-cells and zymogen granules can be seen near them (Plate I:3). The zymogen granules aggregate in the apical cytoplasm. F-cells are believed to be specialized for the synthesis and secretion of digestive enzymes. R-cells are the most numerous cell type. Their nuclei are near the basement of the cells. In some R-cells, there are no vacuoles in the cytoplasm while some R-cells have one or many vacuoles. At different larvae stages, the morphology of R-cells is different. There is one region in the cell where no cytoplasmic organelles exist. This region is nest to the apical cell membrane. Under this region, the number of mitochondria with high electron density matrix and plenty of ridges is very large (Plate I:4). In the proximal cytoplasm near the base of the cell, there is a plenty of smooth endoplasmic reticulum. The number of Golgi bodies is less than that in F-cells, and their morphology differs from that of F-cells. There is much lipid droplet especially near the base of R-cells (Plate I:5). The calcium body can be observed, and its number is very small (Plate I:6). Some R-cells show signs of degeneration. B-cells mainly locate in the proximal regions of the tubules, their volume are the biggest and shapes not regular. There is a big vacuole whose volume may occupy 80%–90% of the whole volume of the cell. There is a thin rim around the vacuole which includes dense cytoplasm, RER and mitochondria. On the top of B-cells, there exists a top complex body consisting dense cytoplasm, pinocytotic vesicles, small mitochondria and microvilli on the surface of B-cells (Plate I:7). Cytosis and intracellular digestive phenomenon can be observed. Observations on the ultrastructure of B-cells show that the formation of B-cells is a progressive process. It is transformed from F-cells. Firstly, the apical cell membrane of F-cells develops invagination which extend as channels deep into the cell to form pinocytotic vesicles. The pinocytotic vesicles move toward the base of the cell and enlarge by fusion with each other to form small digestive bodies. The remaining two thirds of the volume of the cells contain mitochondria and rough endoplasmic reticulum (Plate I:8). With the transformation progressing, pinocytosis becomes increasingly active. Under the pinocytotic system there is a subapical vacuole system. Granules inside the vacuoles coalesce with dense digestive bodies. Small translucent region appears in the digestive body and enlarges gradually (Plate I:9). When such a region replaces the digestive inclusion, the vesicles of B-cells are formed. The vesicle coalesce with subapical vacuole and make the volume of vesicle increase; finally mature B-cells are formed (Plate I:7). Through the present study, the differentiation sequence of four cell types of hepatopancreas in larval Scylla serrata are identified. There are two tendencies for the differentiation of E-cells. Some E-cells develop to F-cells; B-cells are then derived from F-cells. Some other E-cells develop to R-cells, and R-cells degenerate eventually. |
| Key words: Larval Scylla serrata, Hepatopancreas, Microstructure, Ultrastructure |
