Expression of the SMN gene in adult spinal cord. A to C: Anterior horn. A: Antisense probe, bright field; strong expression in the motor neurons. B: Antisense probe, dark field. C: Sense probe. TB (×200). D: Higher magnification of one of the motor neurons from A. TB (×800). E and F: Expression in small neurons of the posterior horn. E: Antisense probe, bright field. F: Sense probe, bright field. TB (×800). G to I: Cells of the central canal expressing high level of SMN transcript. G: Antisense probe, bright field. H: Antisense probe, dark field. I: Sense probe, dark field. TB (×200).