In the amniote embryo, the upper jaw and nasal cavities form through coordinated outgrowth and fusion of craniofacial prominences. Adjacent to the embryonic prominences are the developing eyes, which abut the maxillary and lateral nasal prominences. The embryos of extant sauropsids (birds and nonavian reptiles) develop particularly large eyes in comparison to mammals, leading researchers to propose that the developing eye may facilitate outgrowth of prominences towards the midline in order to aid prominence fusion. To test this hypothesis, we performed unilateral and bilateral ablation of the developing eyes in chicken embryos, with the aim of evaluating subsequent prominence formation and fusion. Our analyses revealed minor interaction between the developing craniofacial prominences and the eyes, inconsequential to the fusion of the upper beak. At later developmental stages, the skull exhibited only localized effects from missing eyes, while geometric morphometrics revealed minimal effect on overall shape of the upper jaw when it develops without eyes. Our results indicate that the substantial size of the developing eyes in the chicken embryo exert little influence over the fusion of the craniofacial prominences, despite their effect on the size and shape of maxillary prominences and components of the skull.

中文翻译：

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鸟类胚胎中发育中的眼睛和颅面突起之间的断开

在羊膜胚胎中，上颌和鼻腔通过协调的长出和颅面突起的融合形成。与胚胎突出部相邻的是发育中的眼睛，它紧靠上颌骨和侧鼻部突出部。与哺乳动物相比，现存的蜥脚类动物（鸟类和非鸟类爬行动物）的胚胎发育出特别大的眼睛，因此研究人员提出，发育中的眼睛可能会促进突起向中线​​的生长，以帮助突起融合。为了验证这一假设，我们对鸡胚胎发育中的眼睛进行了单侧和双侧消融，目的是评估随后的突起形成和融合。我们的分析揭示了发育中的颅面突起和眼睛之间的轻微相互作用，对上喙的融合无关紧要。在发育后期，头骨仅表现出缺失眼睛的局部影响，而几何形态测量学显示，当它在没有眼睛的情况下发育时，对上颌整体形状的影响很小。我们的结果表明，鸡胚胎中发育中的眼睛的相当大的大小对颅面突起的融合几乎没有影响，尽管它们对上颌突起和颅骨组成部分的大小和形状有影响。