I think this answer is fibro-cartilage and I know that these structures in the mouth work  with two other bone formations to allow the mouth to open in the way that it does.  Also, I read somewhere that these mandibular condyle, if fractured, cause sever pain and are very hard to reconstruct.  If left in an impaired condition, they can cause serious deformity to the mouth and face.  This problem is made more serious if the person has not fully finished their growth and development.  The mandible is curved and can rotate. The disc part of this condyle is composed of collage-nous connective tissue, but it has no sensation.  I wish you would post again to tell us how any fracture can be repaired, and what part the this condyle plays in our ability to eat.