Gastrulation and the establishment of the three germ layers in the early horse conceptus
Gastrulation and the establishment of the three germ layers in the early horse conceptus
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DOI：
10.1016/j.theriogenology.2014.04.018
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发表时间：
2014-07-15
期刊：
影响因子：
2.8
通讯作者：
Stout, Tom A. E.
中科院分区：
文献类型：
--
作者：
Gaivao, Maria M. F.;Rambags, Bjorn P. B.;Stout, Tom A. E.
实验研究和实地调查表明，母马在妊娠前 6 周内胚胎丢失是很常见的情况。在发育的前两周内，必须发生许多重要的细胞分化事件，才能产生包含所有三个主要胚层（外胚层、中胚层和内胚层）的可行胚胎。由于中胚层和原条的形成对于胚胎本身的发育至关重要，但尚未在马中得到广泛描述，因此我们结合立体显微镜、光学显微镜和免疫组织化学检查了早期马概念中的组织发育和分化。排卵后第 12 天首次观察到外胚层细胞进入形成中胚层：到第 18 天，孕体完成了一系列分化事件和形态变化，产生了具有功能性循环的胚胎。虽然中胚层前体细胞从排卵后第 12 天开始出现，但直到第 14 天才检测到波形蛋白表达，这表明马中中胚层与外胚层的初始分化独立于这种中间丝蛋白，这种情况与其他驯养物种形成鲜明对比。其他主要胚胎胚层的发育与其他物种相似。例如，外胚层细胞表达细胞角蛋白，并且胚胎外胚层和滋养外胚层之间的染色强度有明显的界限。早在排卵后第10天，下胚层就显示出清晰的甲胎蛋白表达，并且似乎是早期概念中甲胎蛋白的唯一来源。 (C) 2014 Elsevier Inc. 保留所有权利。
Experimental studies and field surveys suggest that embryonic loss during the first 6 weeks of gestation is a common occurrence in the mare. During the first 2 weeks of development, a number of important cell differentiation events must occur to yield a viable embryo proper containing all three major germ layers (ectoderm, mesoderm, and endoderm). Because formation of the mesoderm and primitive streak are critical to the development of the embryo proper, but have not been described extensively in the horse, we examined tissue development and differentiation in early horse conceptuses using a combination of stereomicroscopy, light microscopy, and immunohistochemistry. Ingression of epiblast cells to form the mesoderm was first observed on day 12 after ovulation: by Day 18 the conceptus had completed a series of differentiation events and morphologic changes that yielded an embryo proper with a functional circulation. While mesoderm precursor cells were present from Day 12 after ovulation, vimentin expression was not detectable until Day 14, suggesting that initial differentiation of mesoderm from the epiblast in the horse is independent of this intermediate filament protein, a situation that contrasts with other domestic species. Development of the other major embryonic germ layers was similar to other species. For example, ectodermal cells expressed cytokeratins, and there was a clear demarcation in staining intensity between embryonic ectoderm and trophectoderm. Hypoblast showed clear alpha 1-fetoprotein expression from as early as Day 10 after ovulation, and seemed to be the only source of alpha 1-fetoprotein in the early conceptus. (C) 2014 Elsevier Inc. All rights reserved.