I used to prepare brainstem-spinal cord preparations for recording from nerve roots from lumbar, cervical and brain stem using dorsal approach. I used to that in late embryonic and newborn mice, and you will need a stereomicroscope and a special bath or dish in which you can pin the mice down. For details, see the following paper.
best wishes, Refik
Article Glycinergic and GABAergic Synaptic Activity Differentially R...