三角帆蚌内脏团不同部位插核育珠对珍珠囊形成的影响

Effects of different tissue sites insert-nucleus on pearl-sac formation in visceral mass of Hyriopsis cumingii

对三角帆蚌(Hyriopsis comingii)内脏团不同部位进行插核,研究各组珍珠囊形成、结构以及珍珠质沉积的差异,从而确定出有利于珍珠形成的插核核位。实验选取内脏团5个部位(I:斧足内脏团前端;II:斧足内脏团中部;III:近生殖腺部;IV:近胃部;V:近肾部)进行插核,并分别在插核后第20、50、90、150天(thd)采集内脏团插核部位进行组织固定,利用石蜡切片、HE染色研究不同插核部位珍珠囊结构及珍珠质沉积情况。结果表明:(1)插核施术后20 d,II组插核位点最早形成单层低柱状上皮细胞,为次生珍珠囊;(2)插核施术后50 d,I、II、III组均形成了珍珠囊上皮细胞,而IV、V组插核位点未出现类似的柱状细胞。其中II、III组珍珠囊上皮细胞前端含有大量体积较大的颗粒物;(3)插核施术后90 d,I、III组珍珠囊细胞间出现大量细胞间隙,I、II组珍珠囊表皮细胞具有多核现象的细胞数量增多,且II、III组上皮细胞中颗粒物数量增多,而IV、V组插核位点形成了复层扁平上皮细胞;(4)插核施术后150 d,I、III组珍珠囊内表皮细胞间隙变少。II组珍珠囊上皮细胞游离端存在大量的微绒毛,其与III组相似,珍珠囊上皮细胞细胞核明显增多,颗粒物减少。该时期,IV组在插核位点上形成了不连续的低柱细胞、V组插核位点仍未出现珍珠囊细胞。(5)三角帆蚌在插核术后养殖150 d后,I、II、III组珠核表面出现明显的珍珠质沉积,II、III组珍珠质沉积均匀,I组不均匀,并且II组沉积的珍珠层厚度(0.85 mm±0.06 mm)显著大于I、III组(P<0.05;0.62mm±0.07 mm,0.56 mm±0.03 mm),而IV、V组珠核表面没有珍珠质沉积。研究结果表明,三角帆蚌内脏团不同插核部位珍珠囊上皮细胞的形成存在明显差异,斧足–内脏团前端、斧足–内脏团中部以及近生殖腺部插核能形成完整的珍珠囊结构并沉积珍珠质,其中斧足–内脏团中部插核更有利于珍珠的生长。本研究旨为淡水珍珠贝的内脏团育珠研究工作提供实践基础和理论依据。

In order to probe the feasibility of culturing insert-nucleus pearl in visceral mass of freshwater oyster, the different sites of visceral mass were inserted with nucleus in Hyriopsis cumingii. The morphology, formation and nacre deposition of the pearl sac or insert-nucleus positions were observed after inserting nucleus to confirm inserting-nucleus sites of beneficial pearl formation. The 5 locations in visceral mass were chosen （I：front foot-visceral mass, II：middle foot-visceral mass, III：near reproduction gland, IV：near stomach, V：near kidney）, and mussel was inserted nucleus at these locations. The pearl sac of Hyriopsis cumingii was sampled in the days of 20th, 50th, 90th, and 150th （thd） with operating nucleus, respectively. Then, the formation and pearl formation were observed by the methods of HE staining and paraffin section. To group II, low columnar simple-epithelial cells were formed firstly in 20 thd after inserting nuc-leus, which was secondary pearl sac. Postoperative 50 thd, similar pearl sac epithelial cells were formed at inserting nucleus positions of groups I, II and III, while they was not been detected at these positions of group IV or V. The large granular matter was found at epithelial cells front of groups II and III. Postoperative 90 thd, a large number of intercel-lular spaces were observed at pearl sac of groups I and III. Epidermal cells with multi-nucleus were increased in groups I and II, and the numbers of granular matter of were increased in epithelial cells of groups II and III. But, the stratified squamous epithelium cells were formed in operating positions of groups IV and V. Postoperative 150 thd, intercellular spaces were decreased in pearl sec of groups I and III. Amass of microvillus were found at epithelial cell free-end of pearl sac in group II. Meanwhile, cell nucleuses were increasing and granular matter were decreasing in groups II or III compared to 90 thd. As the same time, discontinuous low columnar cells in treatment IV were found, but these did not appear in group V. The Hyriopsis cumingii were breed with inserting nucleus. The nacre was obvious on the in-serted-nucleus surface in groups I, II or III at postoperative 50 thd, 90 thd, and 150 thd. The results indicated the depo-sitional nacre was evenly distributed for groups II and III, but group I did not. The thickness of pearls lay in group II （0.85 mm±0.06 mm） significantly increased than them in groups I and III （P〈0.05;0.62 mm±0.07 mm, 0.56 mm± 0.03 mm）. Otherwise, there wasn’t nacre deposition on the nucleus surface of groups IV and V. This study confirmed that the formation of the pearl sac epithelial cells existed obviously difference by inserting nucleus in different position of Hy-riopsis cumingii. The complete pearl sac structure could be formed at different sites for front foot-visceral mass, middle foot-visceral mass, near reproduction gland, and then the nacre were deposited. Furthermore, inserting nucleus in mid-dle foot-visceral mass was conducive to pearl growth. This research provided the practical and theoretical foundation for cultivating freshwater pearl in visceral mass.