Evolution of cortical intermediate progenitors and Tbr2 gene functions

为了探讨哺乳动物中间祖细胞的进化起源，我们分析了非哺乳动物苍白球的祖细胞特征。哺乳动物中间祖细胞是tbr2阳性的，在皮层的基底侧进行有丝分裂（基底祖细胞：bp）。相反，BPs和tbr2阳性细胞在发育中的禽苍白膜中是不同的细胞群；前者类似于灵长类动物的外放射状胶质细胞，而后者是有丝分裂后的神经元。我们的研究结果表明，bp在哺乳动物和鸟类谱系中独立进化，这为这两个羊膜动物群体提供了脑功能。

To explore the evolutionary origin of mammalian intermediate progenitors, we analyzed progenitor characteristics in non-mammalian pallium. Mammalian intermediate progenitors are Tbr2-positive and undergo mitosis at the basal side of the cortex (basal progenitors: BPs). On the contrary, BPs and Tbr2-positive cells in the developing avian pallium are distinct cell population; the former resemble outer radial glial cells in primates, whereas the latter are post-mitotic neurons. Our results suggest that BPs have independently evolved in mammalian and avian lineages, which provided encephalization in these two amniote groups.