Lee Y M, Osumi-Yamashita N, Ninomiya Y, Moon C K, Eriksson U, Eto K
Department of Developmental Biology, Graduate School of Dentistry, Tokyo Medical and Dental University, Japan.
Development. 1995 Mar;121(3):825-37. doi: 10.1242/dev.121.3.825.
This study investigates the migration patterns of cranial neural crest cells in retinoic acid (RA)-treated rat embryos using DiI labeling. Wistar-Imamichi rat embryos were treated at the early (9.0 days post coitum, d.p.c.) and late (9.5 d.p.c.) neural plate stages with all-trans RA (2 x 10(-7) M) for 6 hours and further cultured in an RA-free medium. RA exposure stage dependently induced two typical craniofacial abnormalities; that is, at 9.0 d.p.c. it reduced the size and shape of the first branchial arch to those of the second arch, whereas, in contrast, at 9.5 d.p.c. it induced fusion of the first and second branchial arches. Early-stage treatment induced an ectopic migration of the anterior hindbrain (rhombomeres (r) 1 and 2) crest cells; they ectopically distributed in the second branchial arch and acousticofacial ganglion, as well as in their original destination, i.e., the first arch and trigeminal ganglion. In contrast, late-stage treatment did not disturb the segmental migration pattern of hindbrain crest cells even though it induced the fused branchial arch (FBA); labeled crest cells from the anterior hindbrain populated the anterior half of the FBA and those from the preotic hindbrain (r3 and r4) occupied its posterior half. In control embryos, cellular retinoic acid binding protein I (CRABP I) was strongly expressed in the second branchial arch, r4 and r6, while weakly in the first arch and r1-3. CRABP I was upregulated by the early-stage treatment in the first branchial arch and related rhombomeres, while its expression was not correspondingly changed by the late-stage treatment. Moreover, whole-mount neurofilament staining showed that, in early-RA-treated embryos, the typical structure of the trigeminal ganglion vanished, whereas the late-stage-treated embryos showed the feature of the trigeminal ganglion to be conserved, although it fused with the acousticofacial ganglion. Thus, from the standpoints of morphology, cell lineages and molecular markers, it seems likely that RA alters the regional identity of the hindbrain crest cells, which may correspond to the transformation of the hindbrain identity in RA-treated mouse embryos (Marshall et al., Nature 360, 737-741, 1992).
本研究利用DiI标记法，研究视黄酸（RA）处理的大鼠胚胎中颅神经嵴细胞的迁移模式。将Wistar-Imamichi大鼠胚胎在神经板早期（合子后9.0天，d.p.c.）和晚期（9.5 d.p.c.）用全反式视黄酸（2×10⁻⁷ M）处理6小时，然后在无RA的培养基中进一步培养。RA暴露阶段依赖性地诱导两种典型的颅面异常；即，在9.0 d.p.c.时，它将第一鳃弓的大小和形状缩小到第二鳃弓的大小和形状，而相比之下，在9.5 d.p.c.时，它诱导第一和第二鳃弓融合。早期处理诱导后脑前部（菱脑节（r）1和2）嵴细胞异位迁移；它们异位分布在第二鳃弓和听面神经节，以及它们的原始目的地，即第一弓和三叉神经节。相比之下，晚期处理并未干扰后脑嵴细胞的节段性迁移模式，尽管它诱导了融合鳃弓（FBA）的形成；来自后脑前部的标记嵴细胞分布在FBA的前半部分，来自耳前后脑（r3和r4）的标记嵴细胞占据其后半部分。在对照胚胎中，细胞视黄酸结合蛋白I（CRABP I）在第二鳃弓、r4和r6中强烈表达，而在第一弓和r1 - 3中表达较弱。早期处理使第一鳃弓和相关菱脑节中的CRABP I上调，而晚期处理并未相应改变其表达。此外，全胚神经丝染色显示，在早期RA处理的胚胎中，三叉神经节的典型结构消失，而晚期处理的胚胎显示三叉神经节的特征得以保留，尽管它与听面神经节融合。因此，从形态学、细胞谱系和分子标记的角度来看，RA似乎改变了后脑嵴细胞的区域特性，这可能与RA处理的小鼠胚胎中后脑特性的转变相对应（Marshall等人，《自然》360，737 - 741，1992）。
