Apparatus and methods are disclosed for accessing the interior of an intervertebral disc to perform a function within the disc. One such apparatus comprises a catheter having a lumen; and a guide wire having a distal portion and a proximal portion, and configured to be positioned within and moved relative to the lumen of the catheter; wherein the guide wire is capable of navigating itself within an intradiscal section of the intervertebral disc to a selected section of the disc and the catheter is capable of being advanced relative to the guide wire such that the catheter follows a path of the guide wire within the intradiscal section of the disc to the selected section. These apparatus and methods may be used for the treatment of intervertebral disc disorders such as sealing fissures of the annulus fibrosus, which may or may not be accompanied with contained or escaped extrusions. These apparatus and methods may also be used, for example, for the removal or addition of material to the intervertebral disc.