Understanding the development of the craniofacial skeleton using lens ablation and morphometrics

The Mexican tetra, Astyanax mexicanus , is of particular interest in the investigation of interactions between the developing eye and the craniofacial skeleton, as this species exists as two morphs (sighted and blind). We ablated the lens in sighted tetra embryos to investigate this relationship using two methods; manual and laser ablation. After manual ablation, fifty percent of juvenile fish displayed eye regression resulting in one‐eyed adults. Histological and morphometric analyses of one‐eyed fish show that the patterning and development of bone within and surrounding the eye are affected by the absence of the lens. Scleral ossicles are reduced or absent, supraorbital and suborbital bones exceed their usual size and cover the orbit. The effect of lens removal was more dramatic the earlier the surgery was performed. Laser lens ablation facilitates lens removal later in development and results in two‐eyed adults. Surprisingly, the later laser surgery is performed, the more dramatic the effect is on the craniofacial skeleton. Research suggests that the taste and visual systems are linked modules in the Mexican tetra. Therefore, we also investigated the effects of lens ablation on the taste bud development. This research will help to better understand the relationship between the developing eye, skull and gustatory system. Funding provided by Natural Sciences and Engineering Research Council of Canada. Grant Funding Source : NSERC