Attractive effects of the OB on cells migrating along the RMS. A, A diagram of the sagittal section of neonatal rat forebrain showing different parts of the RMS from which explants were isolated and cocultured. X, SVZa; Y, posterior part of RMS; Z, anterior part of the RMS. B, Asymmetric distribution of cells migrating from an SVZa explant cocultured with the OB. C, Symmetric distribution of cells migrating from an SVZa explant cocultured with a cortical explant. D, Asymmetric distribution of cells migrating from an explant from the posterior part of the RMS cocultured with the OB (n = 236 of 291). E, Effects of cortical and OB explants on the distribution of cells migrating out of explants of the SVZa and RMS. The cell numbers were counted from 33 SVZa explants, 32 posterior RMS explants, and 36 anterior RMS explants. CTX, Cortex; RMSp, posterior RMS; RMSa, anterior RMS; P/D, proximal/distal. F, Asymmetric distribution of cells migrating from an anterior RMS explant cocultured with the OB (n = 312 of 372). Scale bar, 100 μm.