不同鱼类肌间骨的骨化模式研究

OSSIFICATION PATTERNS OF INTERMUSCULAR BONES IN DIFFERENT FISH SPECIES

为研究鱼类肌间骨的骨化模式,采用整体骨骼染色方法,对黄鳝(Monopterus albus)和泥鳅(Misgurnus anguillicaudatus)2种处于不同进化地位且游动模式不同的鱼类肌间骨发生发育进行了系统观察。结果显示合鳃鱼目合鳃鱼科且游动模式属于鳗鲡模式的黄鳝在孵出后30d(体长40 mm)时,其头部开始出现椎体小骨;随后依次向尾部骨化,在孵出后55d(体长约100 mm)时,肌间骨相继出现完毕,所有椎体小骨均为"I"形。鲤形目鳅科且游动模式为鲹科模式的泥鳅在孵出后27d(体长17 mm)时,肌间骨开始在尾部出现,包括髓弓小骨和脉弓小骨;随后依次向头部骨化,在孵出后40d(体长35 mm)时,肌间骨全部出现,形态包括"I"、"Y"和"卜"形。此外,研究利用成骨细胞特异性转录因子绿色转基因荧光蛋白(Osterix GFP)斑马鱼品系,通过观察此osterix GFP活体斑马鱼,可发现斑马鱼肌间骨从尾部向头部依次骨化的过程。研究结果揭示鱼类肌间骨的骨化规律与其游动模式密切相关,且肌间骨的形态种类的多态性与其游动模式和体型有一定的关系。

Intermuscular bones, existing only in teleosts among advanced vertebrates, are segmental, serially homologous ossifications in the myosepta. However, there is limited information on the development and ossification of intermuscular bones. In the present study, the morphological development of intermuscular bone in rice eel（Monopterus albus） and weather loach（Misgurnus anguillicaudatus） was investigated using bone clearing and staining method. Study of these two species may imply the evolutionary ossification in teleost due to their different evolutionary status and different swimming modes. The results showed that in M. albus, a typical anguilliform swimmer and belonging to Synbranchidae of Synbgranchiformes, initial intermuscular bones（epicentrals） were ossified at anterior part at 30 days post hatching（dph） with the body length（BL） of 40 mm. Then intermuscular bones were ossified from the anterior to the posterior part. At 55 dph（BL 100 mm）, all the intermuscular bones were basically appeared with all type ＂I＂ epicentral bones. However, in M. anguillicaudatus, carangiform swimmer and belonging to Cobitidae of Cypriniformes, initial intermuscular bones including epineurals and epipleural bones were ossified at posterior part at 27 dph（BL 17 mm）. Then intermuscular bones were ossified from the posterior to the anterior part. At 40 dph（BL 35 mm）, all the intermuscular bones were basically appeared with the types of ＂I＂, ＂Y＂ and ＂卜＂. Moreover, through the use of osteoblast specific transcription factor（osterix） green fluorescent protein transgenic（osterix GFP） zebrafish（Danio rerio）, the process of development and ossification of intermuscular bones were observed in vivo and the results showed that the intermuscular bones were ossified from the posterior to the anterior parts in D. rerio. The results from this study indicated that the ossification of intermuscular bones might be related to fish swimming mode, and their morphological polymorphism may be correlated with fish swimming mode and body type. However, whether the ossification of intermuscular bones has relation with fish phylogenetic evolution needs to be further explored.