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Influence of the eye on neurocranium development; Insights from Mexican cavefish ( Astyanax mexicanus )
Author(s) -
Gimhani Nuwanthika,
Atukorallaya Devi
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.05686
Subject(s) - neurocranium , vomer , anatomy , biology , pectoral girdle , ossification , endochondral ossification , osteology , skull , cartilage
Astyanax mexicanus is being recognized as an intriguing teleost model in developmental biological studies. A. mexicanus exists as two morphs eyed, pigmented surface dwelling morph known as surface fish and an unpigmented blind cave dwelling cavefish. The midline bones of anterior neurocranium of A. mexicanus consists of parasphenoid, ethmoid and vomer bone. The detailed anatomical development of neuorocranial skeleton of this fish is unexplored thus far. The present comparative study is designed to understand the palatal bones, parasphenoid, ethmoid and vomer bone development among surface fish and in two population of cavefish Pachon and Tinaja. Cavefish and surface fish (Astyanax mexicanus ) were included in to this study. Fish were fixed at different time point ranging from 10 dpf, 20 dpf, 35dpf, 60 dpf and 5 year old adults. Alizarin red bone stained were used to stain the skeleton. Dissected samples were examined under the stereo microscope for the ossification sequence of the palatal bones. The micro‐CT images of adult fish were taken using SkyScan micro‐CT imager (Bruker) and CT vox software (Bruker) was used for image analysis. First ossification center appears at the parasphenoid bone at 5 dpf. The anterior neurocranial bones ossified via endochondral ossification. Both cavefish and surface fish ossification starts from the ossification center locate in the center of the parasphenoid cartilaginous palate. Ossification progresses towards anterior direction and merge with the ossifying maxillary bone. The ossification extend up to the notochord in posterior direction. The Micro‐CT images showed that the morphology of parasphenoid bone is different in each eye morph. In surface fish parasphenoid bone curved and it has 20° angle of elevation towards the anterior direction. In contrast, parasphenoid bone found to be straight in Pachon and Tinaja cavefish. Absence of eye structures have an influence on determining the shape of parasphenoid bone. Support or Funding Information We would like to thank the Natural Sciences and Engineering Research Council of Canada (#2019‐05364) for funding this research. We acknowledge the support from University of Manitoba.