Prox1 Influences Neuromast Deposition Frequency and Proliferation in the migrating Posterior Lateral Line Primordium

The posterior lateral line primordium (pLLp) periodically generates neuromasts and deposits them from its trailing end as it migrates from the otic vesicle to the tip of the tail. In this study we have examined the role of the homeodomain transcription factor Prox1in the migrating pLLp. Prox1 is broadly expressed in the pLLp, which contains 2–3 proneuromasts at progressive stages of maturation. Its expression, however, is reduced in nascent sensory hair cells formed by the division of the sensory hair cell precursor located at the center of the most mature proneuromast at the trailing end of the pLLp. Its expression is also absent from inter‐neuromast cells deposited by the migrating pLLp. Knockdown of prox1 with morpholinos reduced both the frequency of neuromast deposition and BrdU incorporation in the pLLp. These changes were associated with expanded expression of Wnt effector lef1 in the pLLp. Our results suggest a role for Prox1 in determining the frequency of neuromast deposition and proliferation in the pLLp