The origin of mesoderm in phoronids.
The origin of mesoderm in phoronids.
复制标题
中胚层的起源。
DOI：
10.1006/dbio.2002.0854
复制
发表时间：
2002
影响因子：
2.7
通讯作者：
M. Martindale
中科院分区：
文献类型：
--
作者：
G. Freeman;M. Martindale
描述性的研究phoronid发展的结论是，这些动物的中胚层起源于原肠胚形成期间的内胚层。这种解释已经通过标记4- 16细胞胚胎的一个卵裂球和检查标记的细胞克隆在幼虫中占据的位置和胚层进行了测试。没有2次注射产生了相同的细胞克隆，表明切割程序不会产生具有独特身份的细胞，并且细胞命运在稍后的发育时间点建立。在许多情况下，标记了由外胚层细胞组成的相对较大的扇区。当这些标记细胞靠近幼虫的口部或肛门时，肌肉和间充质细胞起源于标记克隆。在这种情况下，神经细胞也起源于这些标记的部门。这些标记研究还表明，内胚层细胞可以产生中胚层和神经细胞。这些结果表明，神经和肌肉细胞被诱导形成外胚层-内胚层边界从两个胚层。这些标记实验也证实了神经细胞起源于顶端器官和躯干区域的观察结果，并首次表明肠起源于后外胚层的侵入。
Descriptive studies of phoronid development have concluded that the mesoderm of these animals originates from the endoderm during gastrulation. This interpretation has been tested by labeling one blastomere of 4- through 16-cell embryos and examining the position and germ layers occupied by the labeled clones of cells in the larva. No 2 injections gave rise to identical clones of cells, suggesting that the cleavage program does not generate cells of unique identity and that cell fates are established at later developmental time points. In many cases, a relatively large sector composed of ectodermal cells was labeled. When these labeled cells were adjacent to the mouth or anus of the larva, muscle and mesenchyme cells originated from the labeled clones. Under these circumstances, nerve cells also originated from these labeled sectors. These labeling studies also showed that endodermal cells can give rise to mesodermal and neural cells. These results suggest that nerve and muscle cells are induced to form at ectodermal-endodermal boundaries from both germ layers. These marking experiments also confirmed the observation that nerve cells originate both from the apical organ and the trunk region and show for the first time that the intestine originates by ingression of posterior ectoderm.