SHAPING, INVAGINATION, AND CLOSURE OF THE CHICK-EMBRYO OTIC VESICLE - SCANNING ELECTRON-MICROSCOPIC AND QUANTITATIVE STUDY
SHAPING, INVAGINATION, AND CLOSURE OF THE CHICK-EMBRYO OTIC VESICLE - SCANNING ELECTRON-MICROSCOPIC AND QUANTITATIVE STUDY
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DOI：
10.1002/ar.1092280311
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发表时间：
1990-11-01
影响因子：
--
通讯作者：
NAVASCUES, J
中科院分区：
文献类型：
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作者：
ALVAREZ, IS;NAVASCUES, J
应用扫描电镜、光学显微镜和形态计量学方法研究了内陷和闭合过程中耳板和耳泡的形态学变化。我们的研究结果表明，耳基板经历阶段HH 9和HH 12之间的成型，在此期间的rostrocaudal轴缩短，而基板的lateromedial轴延长。在此期间存在长的胞质分裂桥，表明有丝分裂后的细胞位移可能参与耳基板的形成。成形过程似乎有利于耳基板接近神经管。从HH 12期开始，耳原基逐渐形成一个U形结构，其中间部分与菱脑神经管紧密并置。密切的耳原基-菱脑接触的开始和主动内陷之间的时间巧合表明这两个过程是相关的。在HH 17期耳囊消失之前，耳囊边缘发生的变化表明，除了内陷过程外，耳原基的边缘变得弯曲。在闭合过程中，耳囊边缘的细胞根据其地形位置在顶端形态上不同：吻侧边缘和侧边缘之间的细胞具有细长的顶端，与边缘其他地方的细胞顶端的多边形形状形成对比。在对侧（尾侧和内侧边缘之间）观察到细胞死亡。讨论了概念化为拉链样模型的耳泡闭合。我们提出耳原基的早期发育经历四个阶段：1）成形（阶段HH 9 -11）; 2）触发内陷（阶段HH 12）; 3）早期内陷和侧弯（阶段HH 13 -15）;和4）晚期内陷和闭合（阶段HH 16 -17）。
Scanning electron microscopy, light microscopy, and morphometric analysis were used to study the morphological changes of the otic placode and vesicle before and during invagination and closure processes. Our results reveal that the otic placode undergoes shaping between stages HH9 and HH12; during this period the rostrocaudal axis is shortened, while the lateromedial axis of the placode lengthens. The presence of long cytokinesis bridges during this period suggests that cellular displacements after mitosis may participate in the shaping of the otic placode. The shaping process appears to facilitate the approach of the otic placode to the neural tube. From stage HH12 on, the otic anlage gradually becomes a U-shaped structure with its medial portion in intimate apposition to the rhombencephalic neural tube. The coincidence in time between the beginning of intimate otic anlage-rhombencephalon contact and active invagination suggests that these two processes are related. Changes occurring at the edges of the otic vesicle until their disappearance in stage HH17 suggest that, in addition to a process of invagination, the edges of the otic anlage become bent. During closure, cells at the edges of the otic vesicle differ in apical morphology according to their topographical location: The cells between the rostral and lateral edges have elongated apices, in contrast with the polygonal shape of the cell apices in other places of the edges. In the opposite side (between the caudal and medial edges) cell death is observed. Closure of the otic vesicle conceptualized as a zipper-like model is discussed. We propose that early development of the otic anlage takes place in four stages: 1) shaping (stages HH9-11); 2) triggering of the invagination (stage HH12); 3) early invagination and lateral bending (stage HH13-15); and 4) late invagination and closure (stages HH16-17).