ABSTRACT
Objective This study aims to examine the development of the posterior lateral line of the zebrafish and establish ant model to study the process of hair cell differentiation and regeneration .Methods We observed the posterior lateral line system formation by DAPI immunohistochemistry and whole mount in situ hybridization .We further evaluated hair cells differentiation within neuromast by using Transgenic Tg (Brn3c:mGFP) zebrafish and stained the functional hair cells by the mechanotransduction marker FM 1 -43FX .We labelled proliferating cells in primordium and neuromast by addition of BrdU to the system water .Results The posterior lateral line primordium originated from a sensory placode and started its journey at around 20 hours post fertilization to migrate along the horizontal myoseptum to the tail -tip with a constant speed (1 .7somite/hour) .The primordium depositd five or six neuromasts spaced along the body ,and two or three terminal neuromasts at the tail -tip at 48 hours post fertiliza-tion .At 3 ,5 and 7 days post fertilization ,zebrafish contained 5 .68 ± 1 .46 ,10 .1 ± 0 .99 ,and 12 .45 ± 1 .32 hair cells per neuromast ,respectively .Furthermore ,the average number of FM1-43FX stained hair cells within each neuro-mast were 3 .68 ± 1 .11 ,8 .18 ± 1 .86 ,and 10 .22 ± 1 .24 ,respectively .Conclusion We establish the development model of hair cells in zebrafish lateral line neuromast and suggest that 3 to 7 days post fertilization is an important period for lateral line neuromast differentiation .This study would be useful for underlying the mechanisms of hair cell differentiation and regeneration .