中国对虾幼体中肠的超微结构

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，它由两类细胞组成。第一类细胞在发育早期占多数，随着幼体的发育逐渐减少，至仔虾期后，肠上波完全由第二类细胞组成，基膜分为内、外两层，且在

ULTRASTRUCTURE OF THE MINGUT IN THE LARVAE OF PENAEUS CHINENSIS

Larval Penaeus chinensis (from nauplius topost larvae) were collected from Taoluo Ihawn Breeding Fastory, Rjzhao City, Shandong Province, in April 1995. The dridgut ultrastrucare was observed by TEM. The larval Penaeus chinensis samples were prefixed in 2.5% glutaraldehyde and postfixed in 1% osmic acid. After dehydrihon in a series of graded ethanol, they were transfermd into acetone and embedded in Epon-812. After sitting by the sedri-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 digeshve tube. It consists of three parts, i.e. midgut epithelium, basal membIane and muscular layers. Epithelial cells have abundant microvilli and contrin rich mitochondria, endoplasmic reticulum, Golgi complex and zymogen granules in cytoplasm. Two epithelial cell types can be dishnginshed: the cells conhaning liPid granules (Flg. 1. 1) and the cells lacking lipid granules (Flg. 1:3). The main cell type is the first one at the eariy stage, but in the development process, the first type ceIls become fewer gfadually, and disaPpear at the postlarval stage. Eventually, the ePithelium oniy consistS of the second type cells. The first type cell is similar to the B-cell of the Andgut gland in the strUcfor (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 gnmules are released into the midgut lum. The simildrity in structure further confirms that the whdgut gland is from the midgut and the B-cell is from the first type cell of the nddgut at firsL Because the B-cell partjcipates in cytcrdigeshon in nddgut gland (Al-Mohanna et al, 1986), at the eary stage the Andgut epithelium pAncipates in absorPhon and digeshon before the midgut gland developed. Zymogen and 1ipid gfanules of the first type cells are mainiy used in digeshon. With the gradual nddgutgland development the digeshve funchon of the whdgut is replaced by the midgut gland's. At the mysis stage, the dridgut mainly participates in abeorption. The cell gradually changes from the first type at the early stage to the second type cell. At the POshareal 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 cireular and longitudinal cells (fig. 1: 3, 5), and it thickens gradualy in the development.