Flow cytometry of unlabeled primary cells isolated from intervertebral discs (IVD) of four different species. A. Porcine passage 0 coccygeal IVD cells B. Rabbit passage 0 lumbar IVD cells. C. Bovine passage 0 coccygeal IVD cells, and D. Human passage 0 lumbar IVD cells (L1-2). Note the presence of notochordal cells, which are bigger and spread higher on both forward scatter and side scatter in A. and B. Parameters of flow cytometer were constant for all measurements. Axes are FSC-A = forward scatter, SSC-A = side scatter.