The process in which a relatively unspecialized cell acquires the specialized features of a tendon cell. Tendon cell are elongated fibrocytes in which the cytoplasm is stretched between the collagen fibres of the tendon. Tendon cells have a central cell nucleus with a prominent nucleolus, a well-developed rough endoplasmic reticulum, and are responsible for synthesis and turnover of tendon fibres and ground substance.
muscle attachment cell differentiation