| 摘要: |
| 1995年4月，在山东日照市涛雒对虾育苗场采集中国对虾各期幼体，采用超薄切片和电镜观察的方法，对其中肠结构进行观察研究。结果表明，中国对虾幼体的中肠肠壁由3部分组成，即肠上皮、基膜和肌层。中肠上皮细胞具发达的微绒毛，胞质中富含线粒体、内质网、高尔基复合体及酶原颗粒等，它由两类细胞（含脂肪颗粒的细胞和不含脂肪颗粒的细胞）组成。第一类细胞在发有早期占多数，随着幼体的发育逐渐减少，至仔虾期后，肠上皮完全由第二类细胞组成。基膜分为内、外两层，且在各期中基本无变化。肌层分为环、纵肌层，在发育早期分层不明显，但肌层随着幼体的发育逐渐发达。 |
| 关键词: 中国对虾 幼体 中肠 超微结构 |
| DOI： |
| 分类号: |
| 基金项目:国家攀登计划B资助项目，PD B-6-2-2号 |
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| ULTRASTRUCTURE OF THE MINGUT IN THE LARVAE OF PENAEUS CHINENSIS |
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ZHANG Zhi-feng1, MA Ai-jun2, YU Li1, LIAO Cheng-yi1
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1.College of Marine Life Sciences, Ocean University of Qingdao, Qingdao, 266003;2.Yellow Sea Fisheries Assearch Institute, Chinese Academy of Fishery deiences, Qingdao, 266071
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| Abstract: |
| Larval Penaeus chinensis (from nauplius to post larvae) were collected from Taoluo Prawn Breeding Factory, Rizhao City, Shandong Province, in April 1995. The midgut ultrastructure was observed by TEM. The larval Penaeus chinensis samples were prefixed in 2.5% glutaraldehyde and postfixed in 1% osmic acid. After dehydration in a series of graded ethanol, they were transferred into acetone and embedded in Epon-812. After sitting by the semi-thin section technique, the ultra-thin sections were stained with lead citrate and uranyl acetate. The result shows that midgut is most developed in the digestive tube. It consists of three parts, i.e. midgut epithelium, basal membrane and muscular layers. Epithelial cells have abundant microvilli and contain rich mitochondria, endoplasmic reticulum, Golgi complex and zymogen granules in cytoplasm. Two epithelial cell types can be distinguished: the cells containing lipid granules (Fig.1:1) and the cells lacking lipid granules (Fig.1:3). The main cell type is the first one at the early stage, but in the development process, the first type cells become fewer gradually, and disappear at the post-larval stage. Eventually, the epithelium only consists of the second type cells. The first type cell is similar to the B-cell of the midgut gland in the structure (Wang et al, 1997), with lipid granules in it. The lipid granules change from many small ones to a few large ones. At last, the large lipid granules are released into the midgut lum. The similarity in structure further confirms that the midgut gland is from the midgut and the B-cell is from the first type cell of the midgut at first. Because the B-cell participates in cyto-digestion in midgut gland (Al-Mohanna et al, 1986), at the early stage the midgut epithelium participates in absorption and digestion before the midgut gland developed. Zymogen and lipid granules of the first type cells are mainly used in digestion. With the gradual midgut-gland development, the digestive function of the midgut is replaced by the midgut gland’s. At the mysis stage, the midgut mainly participates in absorption. The cell gradually changes from the first type at the early stage to the second type cell. At the postlarval stage, the cell type changes to the second type completely.
The basal membrane has two layers (Fig.1:3, 4) and there is no change in the development. The muscular layer includes circular and longitudinal cells (Fig.1:3, 5), and it thickens gradually in the development. |
| Key words: Penaeus chinensis, Larvae, Midgut, Ultrastructure |
