During neurogenesis, vertebrate and Drosophila progenitors change over time as they generate a diverse population of neurons and glia. Vertebrate neural progenitors have long been known to use both progenitor-intrinsic and progenitor-extrinsic cues to regulate temporal patterning. In contrast, virtually all temporal patterning mechanisms discovered in Drosophila neural progenitors (neuroblasts) involve progenitor-intrinsic temporal transcription factor cascades. Recent results, however, have revealed several extrinsic pathways that regulate Drosophila neuroblast temporal patterning: nutritional cues regulate the timing of neuroblast proliferation/quiescence and a steroid hormone cue that is required for temporal transcription factor expression. Here, we discuss newly discovered extrinsic cues regulating neural progenitor temporal identity in Drosophila, highlight conserved mechanisms, and raise open questions for the future.

在神经发生过程中，脊椎动物和果蝇的祖细胞会随着时间的推移而发生变化，因为它们会产生多样化的神经元和神经胶质细胞群。众所周知，脊椎动物神经祖细胞同时使用祖细胞内在和祖细胞外在线索来调节时间模式。相反，在果蝇神经祖细胞（神经母细胞）中发现的几乎所有时间模式机制都涉及祖细胞固有的时间转录因子级联。然而，最近的结果揭示了几种调节果蝇的外在途径神经母细胞时间模式：营养线索调节神经母细胞增殖/静止的时间和时间转录因子表达所需的类固醇激素线索。在这里，我们讨论了新发现的调节果蝇神经祖细胞时间特性的外在线索，强调了保守机制，并为未来提出了开放性问题。