López-Román A, Armengol J A
Departamento de Ciencias Morfológicas, Facultad de Medicina, Universidad de Sevilla, Spain.
Neurosci Res. 1996 Oct;26(2):171-9. doi: 10.1016/s0168-0102(96)01100-5.
Naturally occurring neuronal death was found by in situ labelling of nuclear DNA fragmentation during the development of the chick inferior olive. Counting neuronal perikarya showed an evident loss of cells from embryonic day 18 to hatching. This reduction in neuronal numbers was followed by an increase of similar size from days 1-4 post-hatching. This biphasic evolution of the neuronal numbers is quite similar to that found in the inferior olive of rodents during the first two weeks of the postnatal life, a period also characterized by definitive synaptogenesis between climbing fibers and Pukinje cells in the cerebellum of the rodents. The similarity in the evolution of neuronal number in the inferior olive of both rodents and chicks, seems to indicate that definitive synaptogenesis between climbing fibers and Purkinje cells might occur from embryonic day 18 to postnatal day 3 in the chick cerebellum. Nevertheless, during the phase of cell loss the climbing fibers of chick have attained a more mature developmental stage than those of the rat. This difference suggests that naturally occurring neuronal death may be independent of the elimination of redundant axonic collaterals during the definitive climbing fibers-Purkinje cell synaptogenesis.
在鸡延髓下橄榄核发育过程中，通过对核DNA片段进行原位标记发现了自然发生的神经元死亡。对神经元胞体进行计数显示，从胚胎第18天到孵化期，细胞明显减少。神经元数量的这种减少之后，在孵化后第1 - 4天又出现了类似幅度的增加。神经元数量的这种双相变化与啮齿动物出生后前两周延髓下橄榄核中的情况非常相似，这一时期的特点也是啮齿动物小脑中攀缘纤维与浦肯野细胞之间形成确定的突触。啮齿动物和鸡的延髓下橄榄核中神经元数量变化的相似性，似乎表明鸡小脑从胚胎第18天到出生后第3天可能发生攀缘纤维与浦肯野细胞之间的确定突触形成。然而，在细胞丢失阶段，鸡的攀缘纤维比大鼠的攀缘纤维达到了更成熟的发育阶段。这种差异表明，自然发生的神经元死亡可能与确定的攀缘纤维 - 浦肯野细胞突触形成过程中冗余轴突侧支的消除无关。
