Study on embryonic development of Odontobutis potamophila

The embryonic development of Odontobutis potamophila was studied in the present paper.The progress of embryonic development was observed under light microscope and figures were taken once an hour.The results demonstrated that the progress of embryogenesis,which had been lasting for 502 h since fertilization,could be divided into 8 periods including 33 stages.According to the number and size of blastomeres,formation and epiboly extent of the blastoderm,development of the central nervous system,the numbers and formation of somites and the developmental features of the organs,the whole progress was divided into zygote period,cleavage period,blastula period,gastrula period,neural period,segmentation period,pharyngula period and hatching period.Then,the periods could be further divided into sub-stages:the cleavage period into 2～32 cell stages and morula stage;the blastula period into early,middle and late blastula stage;the gastrula period into early,middle and late gastrula stage;the neural period into early and late neural stage;the segmentation period into 2～41 somite stages;the pharynula period into digestive system forming stage,liver forming stage,branchial cleft stage,spleen forming stage,mouth forming stage and swim-bladder forming stage;the hatching period into pre-hatching stage and hatching stage.The stages were named based on the morphological features and other significant events.