Getting out of a mammalian egg: the egg tooth and caruncle of the echidna.
Getting out of a mammalian egg: the egg tooth and caruncle of the echidna.
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从哺乳动物的蛋中取出：针鼹的蛋牙和肉阜。
DOI：
10.1016/j.ydbio.2022.12.005
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发表时间：
2023
影响因子：
2.7
通讯作者：
Fenelon JC
中科院分区：
文献类型：
--
作者：
Fenelon JC
针鼹在子宫内发育后，卵被放在育儿袋里孵化10天。在这段时间里，胎儿长出卵齿和卵爪来帮助它们孵化。利用罕见和前所未有的途径获取有限的针鼹孵化前和孵化后组织，通过显微ct、组织学和免疫荧光技术评估卵齿和腕足的发育情况。针鼹的卵牙是通过外翻发育的，这与一些爬行动物和鱼类的第一批牙齿类似。卵齿与前颌紧密相连，而不是像其他哺乳动物那样形成具有韧带附着的牙根，卵齿的缺失与高水平的破牙细胞活性和细胞凋亡有关。在鸟类和海龟中观察到，鼻部顶部的鼻区上皮表达了角化的标记。总之，这突出表明单目蛋齿与典型爬行动物的牙齿有许多相似之处，表明这颗牙齿是从哺乳动物和爬行动物的共同祖先那里保存下来的。
In the echidna, after developmentin utero, the egg is laid in the pouch and incubated for 10 days. During this time, the fetuses develop an egg tooth and caruncle to help them hatch. Using rare and unprecedented access to limited echidna pre- and post-hatching tissues, development of the egg tooth and caruncle were assessed by micro-CT, histology and immunofluorescence. Unlike therian tooth germs that develop by placode invagination, the echidna egg tooth developed by evagination, similar to the first teeth in some reptiles and fish. The egg tooth ankylosed to the premaxilla, rather than forming a tooth root with ligamentous attachment found in other mammals, with loss of the egg tooth associated with high levels of activity odontoclasts and apoptosis. The caruncle formed as a separate mineralisation from the adjacent nasal capsule, and as observed in birds and turtles, the nasal region epithelium on top of the nose expressed markers of cornification. Together, this highlights that the monotreme egg tooth shares many similarities with typical reptilian teeth, suggesting that this tooth has been conserved from a common ancestor of mammals and reptiles.