Zebrafish cornea formation and homeostasis reflect robustness in camera-type eye biology, regardless of its environment

The cornea is the transparent tissue covering the camera-type eyes. This position makes this tissue prone to environmental aggressions, and physical alteration can have a drastic negative impact on sight. The current knowledge on zebrafish corneal physiology is too scarce to get an understanding on its strategy to maintain a clear sight in aquatic environment. In this study, we focus on corneal formation and maturation in zebrafish. After describing the morphological changes taking place from 3 days post fertilization to adulthood, we analyzed cell proliferation. We show that label retaining cells appear just before 1 month of age. Our cell proliferation study, combined to the study of Pax6a and krtt1c19e expression, demonstrate a long maturation process. This process ends with a solid patterning of corneal innervation. Finally, corneal abrasion wound healing process recapitulates the maturation process, via a plasticity period. Altogether, our study decipher the maturation steps of an aquatic cornea. These findings will facilitate the use of zebrafish as model of corneal physiology studies.