Figure 1. Tight-seal recording from SG neurones in the entire spinal lumbar enlargement.

A, preparation on the entire lumbar enlargement of the spinal cord with preserved unilateral six dorsal roots, L1–L6. The roots were stimulated through suction electrodes. The neurones in the SG were viewed using oblique illumination by infrared LED. B, an image of an SG neurone within the spinal cord. Depth, 43 μm. C, cross sections cut from the fixed spinal cord. The sections of segments L3, L4 and L5 are shown from the preparation used for recordings from the L4 SG neurones. White lines show the border of the grey matter. The border of the grey matter in the cut part of the L4 section is shown as a symmetrical projection of the intact contralateral half. The region of the SG exposed for the patch-clamp recording is indicated by a white arrowhead in segment L4. The images were taken using room illumination (condenser illumination and LED were off) and digitally inverted. D, distribution of ascending and descending primary afferents in the dorsal white matter of a 27-day-old rat. Parasagittal sections from medial (left) and lateral (right) dorsal white matter were from regions indicated on the cross section of the dorsal horn (middle). The cut dorsal root is indicated by an asterisk. In the medial dorsal white matter, several biocytin-labelled thin afferents are indicated by filled arrowheads. In the narrow lateral white matter (right) no stained afferents were detected. Dotted lines show the border between the white and grey matter (in D and E). E, parasagittal section of medial dorsal white matter showing a thin primary afferent entering the grey matter. Parts of the image were taken in different focal planes. F, a 100-μm-thick parasagittal section of the spinal cord with two biocytin-labelled SG neurones. Two dotted lines show the dorsal and ventral borders of the white matter in the focal plane (top of the section). Continuous line shows the dorsal border of the white matter from the bottom of the section.