云南盘[鱼句]仔稚鱼口吸盘发育

Development of the Sucking Disc of Discogobio yunnanensis Larvae and Juveniles

为了解盘[鱼句]属(Discogobio)鱼类口吸盘的发育特点,本研究选取刚出膜的云南盘[鱼句](Discogobio yunnanensis)仔鱼为实验材料,在实验室条件下进行人工养殖,采用体视显微镜、扫描电子显微镜观察云南盘[鱼句]口吸盘的发育过程,利用组织切片的方法观察乳突和味蕾的分布情况,综合分析口吸盘的功能。结果显示,口吸盘的发育可划分为3个时期,即口吸盘形成前期、口吸盘形成期和口吸盘完善期。其中,在口吸盘形成前期,云南盘口吸盘原基尚未形成;在口吸盘形成期,口吸盘各组分原基出现,下唇瓣、肉突、侧突与吸盘主体愈合但仍具缺刻,口吸盘雏形形成;在口吸盘完善期,愈合处缺刻消失,口吸盘发育完整。除马蹄形隆起两侧和中央肉质垫前缘具无乳突分布区外,口吸盘其他区域均布满大小不一的乳突;味蕾主要分布于吻皮、须、唇突、中央肉质垫和口角处。

Discogobio yunnanensis is a small Cyprinid fish, well adapted to flowing water and mainly distributed in Jinsha River, Yuanjiang River, Nanpanjiang River, and Yangtze River. Due to the long-term adaptation to the lotic environment, the lips and related structures have changed accordingly. The lower lip gradually stretches backwards, and the chin uplift is specialized into a mouth-sucker structure with horseshoe folds. However, D. yunnanensis is also named "stone fish" because it likes to scrape the surrounding clumps attached to the stone surface. At water temperature of(20.0±0.5)℃, the unique characteristics in the morphology and histology of the sucking disc of D. yunnanensis larvae and juveniles were observed using light and scanning electron microscopy to understand the characteristics of the sucking disc. The evolution of the sucking disc was classified into three development stages: the pre-forming stage, the forming stage, and the perfecting stage. The primordium of the sucking disc was not formed in the pre-forming stage. In the forming stage, the sucking disc primordium appeared;the lower lip flap, granulation, lateral projection, and the main body of sucking disc were connected as a whole with few gaps, and the prototype of the sucking disc was formed. In the perfecting stage, the gaps disappeared, and the sucking disc was fully developed. There were no mastoids at either side of horseshoe swollen and the leading edge of central pad;however, the other areas of the sucking disc were covered with mastoids of different sizes. Taste buds were mainly distributed in the rostral fold, maxillary barbel, rostral barbel,protuberance of lips, central pad, and corner of the mouth.