EARLY DETERMINATION OF NASAL TEMPORAL RETINOTOPIC SPECIFICITY IN THE EYE ANLAGE OF THE CHICK-EMBRYO
EARLY DETERMINATION OF NASAL TEMPORAL RETINOTOPIC SPECIFICITY IN THE EYE ANLAGE OF THE CHICK-EMBRYO
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DOI：
10.1006/dbio.1995.1022
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发表时间：
1995-01-01
影响因子：
2.7
通讯作者：
THANOS, S
中科院分区：
文献类型：
--
作者：
DUTTING, D;THANOS, S
鸡的视网膜顶盖投射在胚胎第3天至第13天（E3至E13）之间建立。通过局部注射荧光染料DiI和DiA对眼原基的命运映射显示，视泡的前后轴对应于视网膜的鼻颞轴。为了研究视网膜定位特异性在切除部分早期眼原基后的可能改变，我们切除了大部分假定的颞侧或大部分假定的鼻侧眼原基，大约在Hamburger-Hamilton量表的第11阶段（40 - 45小时）。在这样的治疗之后，轴在愈合的视泡中恢复。在愈合过程中，伤口被周围区域的细胞封闭。在早期后（即，用DiI和DiASP逆行和顺行标记鸡胚（E13~E17）和幼鸡（P16）的神经节细胞及其轴突，观察恢复的颞侧半视网膜向视顶盖的投射。正常情况下，只有一小部分来自颞部视网膜的神经节细胞（E13的6.4%和P16的0.08%之间）投射到顶盖的尾部。在实验胚胎和幼龄鸡中，这一比例显着增加（高达80%）。头端和尾端顶盖的逆行双标记显示，颞细胞投射到头端或尾端顶盖上，但不通过两个区域上的侧枝。在颞视网膜内具有“移位鼻”身份的神经节细胞在很大程度上被分离成不同的簇，表明它们来自少数甚至可能是单个祖细胞。同样，视泡前半部分的消融导致了在恢复的鼻侧视网膜内具有"移位的颞侧"身份的吻侧投射细胞簇。在这些实验中，背腹侧视网膜顶盖的关系保持完整。最简单的，但不是唯一的解释的结果是，位置信息是强加的颞鼻阶跃功能已经在多能祖细胞的神经节细胞在眼原基的阶段11或更早。在视泡愈合期间，当一种规格的细胞被另一种规格的细胞包围时，位置值保持稳定。(C)出版社：Academic Press
The retinotectal projection of the chick is established between Embryonic Days 3 and 13 (E3 to E13). Fate mappings of the eye anlage by local injections of the fluorescent dyes DiI and DiA revealed that the anteroposterior axis of the optic vesicle corresponds to the nasotemporal axis of the retina. To investigate possible alterations in retinotopic specificity after ablating parts of the early eye anlage, we resected either most of the presumptive temporal or a large part of the presumptive nasal half of the eye anlage around stage 11 of the Hamburger-Hamilton scale (40-45 hr). After such treatment, the axes are restored in the healed optic vesicle. In the healing process the wound is closed by cells moving in from surrounding areas. After early posterior (i.e., temporal) ablation, the projection from the restored temporal half-retina onto the optic tectum was examined in embryos (E13 to E17) and juvenile chicken (P16) by retrograde and anterograde labeling of ganglion cells and their axons with DiI and DiASP. Normally, only a small fraction of ganglion cells from the temporal retina (between 6.4% on E13 and 0.08% on P16) projects onto the caudal part of the tectum. In experimental embryos and juvenile chicken this fraction is significantly increased (up to 80%). Retrograde double-labeling from the rostral and the caudal tectum reveals that temporal cells project onto either the rostral or the caudal tectum, but not via collaterals upon both areas. The ganglion cells with ''displaced nasal'' identity within the temporal retina that were backlabeled from the caudal tectum were to a large extent segregated into distinct clusters, indicating their derivation from few or possibly even single progenitor cells. Likewise, ablation of the anterior half of the optic vesicle led to clusters of rostrally projecting cells of ''displaced temporal'' identity within the restored nasal retina. In these experiments the dorsal-ventral retinotectal relationship remained intact. The simplest, though not exclusive interpretation of the findings is that positional information is imposed as a temporal-to-nasal step function already on the multipotent progenitors of the ganglion cells in the eye anlage by stage 11 or earlier. The positional values remain stable when during the healing of the optic vesicle cells of one specification become surrounded by cells of another specification. (C) 1995 Academic Press, Inc.