Nerve cell growth. Fluorescent light micrograph of PC12 cells following stimulation by nerve growth factor. The cell bodies contain the nuclei (blue). The initially spherical cells have formed long branching extensions called neurites (green and pink). These neurites would form the axons and dendrons that connect nerve cells and transmit nerve impulses around the body, and the brain and spinal cord. PC12 cells are derived from a tumour of the adrenal gland (pheochromocytoma). Research into curing spinal paralysis uses nerve tissue cultures to investigate neural regeneration. Magnification: x980 when printed 10cm wide.