An elongated fibrocyte that is part of a tendon. The cytoplasm is stretched between the collagen fibres of the tendon. They have a central cell nucleus with a prominent nucleolus. Tendon cells have a well-developed rough endoplasmic reticulum and they are responsible for synthesis and turnover of tendon fibres and ground substance. [ http://www.ncbi.nlm.nih.gov/pubmed/957445 ]