Biology Department, College of Science, Taibah University, Al-Madinah Al-Munawwarah, Saudi Arabia.
Zoology Department, Faculty of Science, Fayoum University, Fayoum, Egypt.
J Anat. 2020 Jan;236(1):117-131. doi: 10.1111/joa.13081. Epub 2019 Sep 1.
Non-avian reptiles are good models to investigate structural and developmental differences between amniotes. Investigations of craniofacial development in a complete series of embryos from oviposition up to hatching are still relatively rare. Consideration of a complete series can reveal developmental events that were previously missed, and thus correct or confirm theories about developmental events. The Egyptian Sand snake, Psammophis sibilans, has been a key species in descriptions of the snake skull development. However, published work was based on a limited sample of specimens collected from the wild. Here, we supplement previous descriptions with an illustrated account of skull development in P. sibilans based on a staged series of embryos and histological sections. Our findings largely agree with those of previous authors, although we record differences in developmental timing, confirming the presence of an egg tooth in this species. We add further observations on the enigmatic fenestra X, showing that it closes rather than merging with the prootic notch. Our observations revealed the likely contribution of the tectum posterius to the occipital roof, the presence of an internal carotid foramen (possibly transitory or variable), and the formation of the initial laterosphenoid pillar.
非鸟类爬行动物是研究羊膜动物结构和发育差异的良好模型。对从产卵到孵化的完整系列胚胎的颅面发育进行研究仍然相对较少。考虑完整系列可以揭示以前错过的发育事件，从而纠正或证实关于发育事件的理论。埃及沙蛇（Psammophis sibilans）一直是蛇头骨发育描述的关键物种。然而，已发表的工作基于从野外收集的有限样本的标本。在这里，我们通过对胚胎分期系列和组织学切片的研究，对 P. sibilans 的头骨发育进行了说明性的描述，补充了以前的描述。我们的发现与以前的作者基本一致，尽管我们记录了发育时间的差异，证实了该物种存在卵齿。我们对神秘的窗 X 进行了进一步的观察，表明它关闭而不是与前耳突切迹融合。我们的观察结果表明，后脑盖极可能由后脑参与形成，存在颈内动脉孔（可能是暂时的或可变的），并形成初始外侧蝶骨柱。
