Cilia in Brain Help New Neurons Find Their Way

Neurons migrate to the olfactory bulb with help of beating cilia

THURSDAY, Jan. 12 (HealthDay News) -- In the adult brain, new neurons migrate along a flow of cerebrospinal fluid created by the beating cilia of epithelial cells, according to the results of a study in mice published in the Jan. 12 issue of Science. The flow allows the neurons to migrate from the subventricular zone along the walls of the lateral ventricle to the olfactory bulb.

Kazunobu Sawamoto, Ph.D., of the Keio University School of Medicine in Tokyo, Japan, and colleagues conducted a number of studies and found that the cilia in the ependyma (epithelial cells lining the lateral ventricle) beat in a steady and coordinated fashion to create a directional stream of cerebrospinal fluid. The researchers also showed that the fluid stream carries a gradient of signaling factors that helps guide the neurons toward the olfactory bulb.

The researchers compared Tg737orpk mutant mice, which have a mutation that interrupts cilia formation, to normal mice. They injected labeled cells into the subventricular zone and found that five days later, 64.6% of cells were in the olfactory bulb in wild-type mice compared with 9.3% in the mutant mice.

"The present work suggests that polarized epithelia and motile cilia in the brain appear to serve as important conveyors of directional information for neuronal migration," the authors conclude.

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