Gaillard Afsaneh, Nasarre Cécile, Roger Michel
CNRS: UMR 6558, Biomembranes et Signalisation Cellulaire, Université de Poitiers, PBS, Faculté des Sciences, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex, France.
Eur J Neurosci. 2003 Apr;17(7):1375-83. doi: 10.1046/j.1460-9568.2003.02576.x.
To help understand how the cortical map is set up during the early stages of corticogenesis, we have examined the developmental fate of embryonic day (E) 12 cortical progenitors in the rat. We have analysed the pattern of thalamic connections and cytoarchitectonic organization developed by progenitor cells removed at E12 from the presumptive parietal or occipital cortex and grafted into the parietal cortex of newborn hosts. Occipital progenitors grafted into the parietal cortex differentiated into neurons that developed reciprocal connections with the ventrobasal complex of the host thalamus. They could also form barrel-like structures, within which axons of the ventrobasal complex were distributed in dense patches. Some of these barrel-like structures were arranged in rows. Moreover, these progenitors failed to develop characteristic traits of occipital cortex cells as they did not establish connections with the dorsal lateral geniculate nucleus. We propose that cortical progenitors are not committed at E12 and, upon heterotopic transplantation, have the capacity to respond to local cues and to subsequently differentiate and maintain major phenotypic characteristics of neurons in their new environment. Only early progenitors are multipotent. By E13/E14, indeed, most cortical cells become irreversibly committed and upon heterotopic transplantation differentiate neurons with phenotypic characteristics of their cortical site of origin (Pinaudeau et al., 2000, Eur. J. Neurosci., 12, 2486-2496).
为了帮助理解皮质图谱在皮质发生早期阶段是如何建立的，我们研究了大鼠胚胎第12天（E12）皮质祖细胞的发育命运。我们分析了从推定的顶叶或枕叶皮质在E12取出并移植到新生宿主顶叶皮质的祖细胞所形成的丘脑连接模式和细胞结构组织。移植到顶叶皮质的枕叶祖细胞分化为与宿主丘脑腹侧基底复合体形成相互连接的神经元。它们还能形成桶状结构，腹侧基底复合体的轴突密集分布于其中。其中一些桶状结构排成行。此外，这些祖细胞未能发育出枕叶皮质细胞的特征性特性，因为它们没有与背侧外侧膝状体核建立连接。我们提出，皮质祖细胞在E12时并未定型，在异位移植后，有能力对局部信号作出反应，并随后在新环境中分化并维持神经元的主要表型特征。只有早期祖细胞具有多能性。事实上，到E期13/14时，大多数皮质细胞变得不可逆转地定型，在异位移植后分化出具有其皮质起源部位表型特征的神经元（皮诺多等，2000年，《欧洲神经科学杂志》，第12卷，第2486 - 2496页）。
