CELL LINEAGE CONVERSION IN THE SEA-URCHIN EMBRYO
CELL LINEAGE CONVERSION IN THE SEA-URCHIN EMBRYO
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DOI：
10.1016/0012-1606(88)90220-5
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发表时间：
1988-02-01
影响因子：
2.7
通讯作者：
MCCLAY, DR
中科院分区：
文献类型：
--
作者：
ETTENSOHN, CA;MCCLAY, DR
海胆胚胎的中胚层通常分为两个细胞群;初级间充质细胞（PMC），其产生幼虫骨架，和次级间充质细胞（SMC），其分化成各种细胞类型，但不参与骨骼发生。在这项研究中，我们研究了胚胎的形态发生，其中PMC已被显微手术去除。我们证实了Mrsanushi（1972）的观察，即缺乏PMC的胚胎形成完整的骨骼，尽管是以延迟的方式。我们通过显微外科手术和细胞标记实验证明，在这种PMC缺陷的胚胎中出现骨骼发生细胞完全是由于其他细胞向PMC表型的转换。对PMC缺陷胚胎的延时录像表明，转换细胞是晚期进入SMC的一个亚群。这些细胞转化为成骨表型伴随着它们通常是PMC特有的细胞表面决定簇的从头表达，如麦胚凝集素和PMC特异性单克隆抗体的结合所示。已经进行了细胞移植和细胞标记实验，以确定当胚胎中存在中等数量的PMC时转化的SMC的数量。这些实验表明，转换SMC的数量与囊胚腔中PMC的数量成反比。此外，他们表明，PMC和转换SMC合作，以产生一个骨架，是正确的大小和配置。这种调节系统应该揭示控制细胞分化的细胞-细胞相互作用的本质，以及进化过程修改发育程序的方式。
The mesoderm of the sea urchin embryo conventionally is divided into two populations of cells; the primary mesenchyme cells (PMCs), which produce the larval skeleton, and the secondary mesenchyme cells (SMCs), which differentiate into a variety of cell types but do not participate in skeletogenesis. In this study we examine the morphogenesis of embryos from which the PMCs have been removed microsurgically. We confirm the observation of Fukushi (1972) that embryos lacking PMCs form a complete skeleton, although in a delayed fashion. We demonstrate by microsurgical and cell marking experiments that the appearance of skeletogenic cells in such PMC-deficient embryos is due exclusively to the conversion of other cells to the PMC phenotype. Time-lapse video recordings of PMC-deficient embryos indicate that the coverting cells are a subpopulation of late-ingressing SMCs. The conversion of these cells to the skeletogenic phenotype is accompanied by their de novo expression of cell surface determinants normally unique to PMCs, as shown by binding of wheat germ agglutinin and PMC-specific monoclonal antibody. Cell transplantation and cell marking experiments have been carried out to determine the number of SMCs that convert when intermediate numbers of PMCs are present in the embryo. These experiments indicate that the number of converting SMCs is inversely proportional to the number of PMCs in the blastocoel. In addition, they show that PMCs and converted SMCs cooperate to produce a skeleton that is correct in both size and configuration. This regulatory system should shed light on the nature of cell-cell interactions that control cell differentiation and on the way in which evolutionary processes modify developnental programs.