Fig. 1

Spinal column isolation and cleaning for bisection. a Extract the spinal column from the base of the skull to just caudal to the femurs, as outlined previously [9]. A side aspect of the column is presented. R, rostral; C, caudal, D, dorsal; V, ventral. b, c Using curved scissors, carefully cut away tissue (e.g. muscle) surrounding the column so that the most caudal pair of ribs, which are floating ribs, can be identified (arrows in c identify each end of a single rib from this pair, and the dashed line indicates exactly where to transect the column in a later step of the procedure). The ventral aspect of the column is presented in both panels. Panel c is the magnified region outlined by the dashed box in b. d To aid subsequent bisection down the mid-line, remove additional tissue exterior to the column, leaving intact the most caudal pair of ribs (arrows) to locate the spinal level. The ventral aspect of the column is presented. (e) The same side aspect is presented as that shown in a, highlighting the impact of tissue removal. See Additional file 1 for a video depicting the subsequent steps of spinal column transection and bisection. Scale bars = 1 cm (a, b, d, e) and 1.5 mm (c)