美洲鲥仔稚鱼脊柱及附肢骨骼系统的早期发育

Early development of the vertebral column and appendicular skeleton of Alosa sapidissima

使用软骨-硬骨双染色技术,描述了美洲鲥(Alosa sapidissima)仔稚鱼(1~51日龄)脊柱、胸鳍、尾鳍、背鳍等附肢骨骼的形态发育特征。结果显示,脊柱的发育开始于10日龄仔鱼尾部的髓弓、脉弓和尾下骨的出现,16日龄髓弓和脉弓延伸形成髓棘和脉棘,19日龄脊柱出现分节的硬骨环,23日龄所有椎体形成。各附鳍支鳍骨发育顺序先后依次为胸鳍、尾鳍、背鳍、臀鳍和腹鳍。胸鳍在2日龄时出现乌喙骨,13日龄形成软骨质的胸鳍支鳍骨,19日龄仔鱼肩带和上匙骨开始骨化;尾鳍的尾下骨最早出现在5日龄,12日龄尾鳍形成2枚尾上骨、1枚尾杆骨和6枚尾下骨,19日龄仔鱼尾椎和尾鳍率先开始骨化,直至23日龄尾鳍骨骼系统钙化完全。最终背鳍和臀鳍分别形成18和22根鳍条。美洲鲥骨骼发育研究对其早期发育功能趋向、环境优化及分类鉴定有重要作用。

Alosa sapidissima is a fish that migrates to spawn, displays rapid growth and high economic value, and is a good substitute food for Tenualosa reevesii. Some studies have reported skeletal development of Clupea pallasii, Opisthonema oglinum, Engraulis japonicus, Sardinops melanostictus, and Coilia nasus in detail, but not that of A. sapidissima. In this study, development of the vertebral column and pectoral and caudal fins of A. sapidissima larvae （1-51 days post hatching[dph]） is described using a cartilage and bone clearing and staining technique. The results show that the vertebral column started to develop from hemal arches, neural arches, and hypurals at 10 dph. The neural and hemal arches extended to the neural and hemal spines at 16 dph, respectively. Segmental bone rings formed at 19 dph, and the vertebral column was completely ossified by 23 dph. The appendicular skeleton developed in sequence from the pectoral, caudal, dorsal, and anal to ventral fins. Development of the pectoral fins started when the coracoid appeared at 2 dph. Cartilage of the appendicular pectoral fins formed at 13 dph, and the pectoral girdle and cleithrum ossified by 19 dph. The caudal fin began to develop when the hypurals appeared at 5 dph, and two sections of the epural, one section of the urostyle, and six sections of the hypurals formed at 12 dph. The caudal vertebra and caudal fin began to ossify 19 dph and were completed by 23 dph. The dorsal and anal fins ultimately developed 18 and 22 fins, respectively. The order of development of the A. sapidissima appendicular skeleton was the same as that of other fish. The appendicular skeleton, hemal arches, hemal spines, neural arches, neural spines, dorsal ribs, and ventral ribs had cartilage ossification stages. The vertebra and supracleithrum were formed directly from the periosteum, as cartilage staining had no effect on vertebra or the cletthrum. Developmental deformities were detected in trunk vertebra, but the rate was lower than that observed in C. nasus. Some caudal vertebrae grew abnormally during the trial. Early exercise had an effect on deformity of longer caudal vertebrae. However, caudal vertebrae lacked protection from forks in the neural arch and ventral ribs. Abnormal growth may have occurred due to nutrition, water quality, or other factors. Studying the early development of the vertebral column and pectoral and caudal fins of A. sapidissima is important to understand functional adaptation during early development, environmental optimization, and to classify and identify fish.