Volumetric tracking of migratory melanophores during zebrafish development by optoacoustic microscopy.

Unveiling mechanisms driving specification, recruitment and regeneration of melanophores is key in understanding melanin-related disorders. This study reports on the applicability of a hybrid focus optoacoustic microscope (HFOAM) for volumetric tracking of migratory melanophores in developing zebrafish. The excellent contrast from highly-absorbing melanin provided by the method is shown to be ideal for label-free dynamic visualization of melanophores in their unperturbed environment. We established safe laser energy levels that enable high-contrast longitudinal tracking of the cells over an extended period of developmental time without causing cell toxicity or pigment bleaching. Owing to its hybrid optical and acoustic resolution, the new imaging technique can be seamlessly applied for noninvasive studies of both optically-transparent larval as well as adult stages of the zebrafish model organism, which is not possible using other optical microscopy methods.