Graziadei P P, Levine R R, Graziadei G A
Proc Natl Acad Sci U S A. 1978 Oct;75(10):5230-4. doi: 10.1073/pnas.75.10.5230.
We removed the right olfactory bulb in neonatal mice, leaving the bulb on the left side intact as an internal control. At 5 days of survival time, we observed that the right cerebral hemisphere was displaced forward to occupy the region made vacant by removal of the bulb. The frontal cortex was, consequently, in close proximity to the lamina cribrosa. As a result of bulb ablation and severance of the fila olfactoria, the sensory perikarya underwent total retrograde degeneration, which peaked at 8 days. New neurons differentiated in the neuroepithelium from basal stem cells and, at 30 days of survival, mature sensory neurons were reconstituted. These new elements sent their axons through the lamina cribrosa to reach the protruding cerebral hemisphere, penetrating it and forming glomeruli-like structures directly in the host tissue. The "glomerulization" of the sensory fibers persisted and actually expanded between 60 and 120 days. The new glomeruli were organized intimately within the brain tissue, and large neurons of the cortex were observed to be in close proximity. Ultrastructural observations of the newly formed glomeruli demonstrated that typical sensory axon terminals profusely branched and synapsed with unidentified postsynaptic processes that penetrated the glomeruli from the surrounding cerebral tissue.
我们切除了新生小鼠的右侧嗅球，保留左侧嗅球完整作为内部对照。在存活5天时，我们观察到右侧大脑半球向前移位，占据了因切除嗅球而腾出的区域。因此，额叶皮质紧邻筛板。由于嗅球切除和嗅丝切断，感觉神经元胞体发生完全逆行性变性，在8天时达到高峰。神经上皮中的基底干细胞分化出新的神经元，在存活30天时，成熟的感觉神经元得以重建。这些新的神经元将它们的轴突穿过筛板，到达突出的大脑半球，穿透该半球并直接在宿主组织中形成类似肾小球的结构。感觉纤维的“肾小球化”持续存在，并在60至120天之间实际扩大。新的肾小球紧密地组织在脑组织内，观察到皮质的大神经元与之紧邻。对新形成的肾小球的超微结构观察表明，典型的感觉轴突终末大量分支，并与从周围脑组织穿透肾小球的未识别的突触后过程形成突触。
