Early onset of the rat olfactory bulb projections
Early onset of the rat olfactory bulb projections
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DOI：
10.1016/0306-4522(95)00360-u
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发表时间：
1996-01-01
期刊：
影响因子：
3.3
通讯作者：
Valverde, F
中科院分区：
文献类型：
--
作者：
LopezMascaraque, L;DeCarlos, JA;Valverde, F
使用荧光碳菁示踪剂DiI，我们详细检查了从大鼠嗅球发出的投影的早期发展。研究在胚胎第13天开始，此时可以检测到第一批纤维，并在胚胎第20天结束，此时所有主要纤维系统都已建立。胚胎第13天，第一批轴突从嗅球区产生。标记纤维具有精致的轴突生长锥体，穿过脑端囊泡的腹外侧部分。在胚胎第14天，虽然主要纤维束还没有进一步发育，但一些孤立的纤维位于离未来嗅球很远的地方。这些早期纤维显然在一个狭窄的无细胞空间内运动，沿着脑端囊泡的腹外侧部尾部延伸。在胚胎第15天，许多有标记的纤维形成紧密的束，与侧嗅束相对应，最终到达预期的初级嗅皮层。这些纤维不会停止生长，而是在胚胎第17天继续向尾端延伸。本研究结果为嗅觉系统轴突束的发育提供了新的信息。我们发现嗅束投射的发育早于嗅球的形态外观。这表明嗅觉投射的早期发展可能不依赖于嗅觉上皮轴突的到来，因此，可能由神经元固有的因素和/或目标环境中存在的线索控制。
Using the fluorescent carbocyanine tracer DiI, we examined in detail the early development of the projections emanating from the rat olfactory bulb. The study commenced at embryonic day 13 when the first fibres can be detected and ended at embryonic day 20, when all major fibre systems have been established. The first axons arising from the prospective olfactory bulb area are seen at embryonic day 13. Labelled fibres are provided with elaborate axonal growth cones advancing through the ventrolateral part of the telencephalic vesicle. At embryonic day 14, while the main fibre tract has not developed much further, some isolated fibres are located quite distally from the prospective olfactory bulb. These early fibres apparently course within a narrow cell-free space that extends caudally along the ventrolateral part of the telencephalic vesicle. At embryonic day 15, a number of labelled fibres form a compact bundle, corresponding to the lateral olfactory tract, that ultimately reaches the prospective primary olfactory cortex. The fibres do not stop growing, but continue to extend caudally at embryonic day 17.The results of this study provide new information on the development of axonal tracts in the olfactory system. We show that the olfactory tract projection develops earlier than the morphological appearance of the olfactory bulbs. This suggests that the early development of olfactory projections might not depend on the arrival of the olfactory epithelium axons and thus, could be governed by factors intrinsic to the neurons and/or cues present in the target environment.