IS THE CEREBELLAR OLIGODENDROCYTE DERIVED FROM THE BRAINSTEM?

研究表明，脊椎动物的脊髓少突胶质细胞在发育早期出现在毗邻底板的腹侧脑室带。由于脊髓和后脑的基本结构相似，可能后脑早期少突胶质细胞的发育模式与脊髓相同。我们在鸡胚胎中用O1和O4单抗检测了这种可能性，O1和O4是少突胶质细胞谱系的标志。在E5雏鸡腹侧后脑内侧脑室带(最早观察到的)靠近底板的部位观察到一个O4阳性(O4+)细胞灶。E6时，O4+细胞从脑桥内侧向外侧散在分布；E7时，O4+细胞散在分布于小脑神经元内。E6脑干和E7小脑中的O4+细胞呈单极状，1天后部分标记细胞呈多极，突起稀疏。O1+少突胶质细胞最早出现在E8…更多分布于脑桥腹内侧部，在胎龄10d分布于脑桥各部，胎龄12d分布于小脑。分别培养E5~E8鸡胚胎后脑三个亚区(桥脑内侧、小脑和小脑)的外植体，以确定其分化为少突胶质细胞系的可能性。O4+细胞见于E5内侧脑桥培养(最早出现)、E6外侧脑桥和E7小脑。此外，E7是小脑外植体能够产生O1+少突胶质细胞的最年轻时期。我们的结果清楚地证明了后脑内少突胶质前体细胞的活体形态以及它们以腹向背侧的方式发育。根据O4+细胞的双极形态和弥散的时空连续性，推测O4+细胞的初始弥散可能涉及少突胶质细胞从桥脑内侧焦点向后脑外侧和背部的迁移。较少

It has been demonstrated that the spinal cord oligodendrocytes in the vertebrates arise in the ventral ventricular zone adjacent to the floor plate in their early development. Because of the similarities of basic structures in the spinal cord and metencephalon, it is probable that the mode of early oligodendrocyte development in the metencephalon is the same as that in the spinal cord. We examined this possibility in chick embryos, using monoclonal antibodies O1 and O4, markers for oligodendrocyte lineage. An O4-positive (O4+) cell focus was observed in the medial ventricular zone of E5 chick ventral metencephalon (the earliest stage examined), adjacent to the floor plate. At E6, O4+ cells were dispersed from the medial to the lateral pons, and at E7, to the cerebellar anlagen. O4+ cells in the E6 brainstem and in the E7 cerebellum were unipolar in shape, while one day later, some of the labeled cells were multipolar with a few thin processes. O1+ oligodendrocytes first appeared at E8 … More in the ventromedial part of the pons, and were distributed throughout the pons at E10 and in the cerebellum at E12. Explants from three subdivisions of the metencephalon (medial and lateral pons, and cerebellum) from E5 to E8 chick embryos were separately cultured to confirm the potential for generation of oligodendrocyte lineage. O4+ cells appeared in the culture of the E5 medial pons (the earliest stage examined), in the E6 lateral pons, and in the E7 cerebellum. In addition, E7 was the youngest stage from which cerebellar explants were able to generate O1+ oligodendrocytes. Our results clearly demonstrated the in vivo morphology of oligodendrocyte precursors in the metencephalon and their developmental appearance in a ventral-to-dorsal manner. From the bipolar morphology of O4+ cells and the spacio-temporal continuity of the dispersion, it is inferred that the initial dispersion of O4+ cells may involve oligodendrocyte migration from the focus of the medial pons to the lateral and dorsal parts of the metencephalon. Less