卵生蛇绒毛尿囊膜的功能复杂性：从蛋壳中摄取钙的特化,Journal of Experimental Zoology-B: Molecular and Developmental Evolution

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卵生蛇绒毛尿囊膜的功能复杂性：从蛋壳中摄取钙的特化
Journal of Experimental Zoology-B: Molecular and Developmental Evolution ( IF 1.8 ) Pub Date : 2022-06-02 , DOI: 10.1002/jez.b.23146
Tom W Ecay ₁ , James R Stewart ₂ , Maleka Khambaty ₁

Affiliation

卵生爬行动物的尿囊绒毛膜与蛋壳形成血管界面。蛋壳含有钙，主要是碳酸钙。绒毛尿囊膜对钙的提取和动员对胚胎营养有重要贡献。绒毛尿囊膜的发育主要从有鳞动物和鸟类的研究中得知。尽管蛋壳结构存在显着差异，但鳞状动物和鸟类胚胎都从蛋壳中调动钙。鸡绒毛膜上皮中的特化细胞在第二群细胞的帮助下从蛋壳中运输钙，这些细胞分泌由碳酸酐酶产生的质子。钙转运细胞也存在于玉米蛇的绒毛尿囊膜中，尽管这些细胞的功能与鸡不同。我们使用组织学和免疫组织学来表征玉米蛇绒毛尿囊膜的形态和功能属性。我们在绒毛膜上皮的外层发现了两个细胞群。钙结合蛋白-D_28K是一种在鳞状绒毛膜尿囊膜中表达的钙转运细胞标志物，位于绒毛膜上皮中占优势的大型扁平细胞中。散布在大细胞中的较小细胞表达碳酸酐酶 2，这是一种以前未定位于卵生鳞状动物的绒毛膜上皮的酶。这些发现表明，绒毛膜上皮细胞的分化有助于从蛋壳中提取和运输钙。从鸡和玉米蛇的蛋壳中吸收钙的特殊尿囊膜的存在表明，蛋壳钙是蜥脚类进化早期胚胎营养的来源。

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Functional complexity in the chorioallantoic membrane of an oviparous snake: Specializations for calcium uptake from the eggshell

The chorioallantoic membrane of oviparous reptiles forms a vascular interface with the eggshell. The eggshell contains calcium, primarily as calcium carbonate. Extraction and mobilization of this calcium by the chorioallantoic membrane contributes importantly to embryonic nutrition. Development of the chorioallantoic membrane is primarily known from studies of squamates and birds. Although there are pronounced differences in eggshell structure, squamate and bird embryos each mobilize calcium from eggshells. Specialized cells in the chicken chorionic epithelium transport calcium from the eggshell aided by a second population of cells that secrete protons generated by the enzyme carbonic anhydrase. Calcium transporting cells also are present in the chorioallantoic membrane of corn snakes, although these cells function differently than those of chickens. We used histology and immunohistology to characterize the morphology and functional attributes of the chorioallantoic membrane of corn snakes. We identified two populations of cells in the outer layer of the chorionic epithelium. Calbindin-D_28K, a cellular marker for calcium transport expressed in squamate chorioallantoic membranes, is localized in large, flattened cells that predominate in the chorionic epithelium. Smaller cells, interspersed among the large cells, express carbonic anhydrase 2, an enzyme not previously localized in the chorionic epithelium of an oviparous squamate. These findings indicate that differentiation of chorionic epithelial cells contributes to extraction and transport of calcium from the eggshell. The presence of specializations of chorioallantoic membranes for calcium uptake from eggshells in chickens and corn snakes suggests that eggshell calcium was a source of embryonic nutrition early in the evolution of Sauropsida.

更新日期：2022-06-02

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