Fig. 1A–B.

(A) Histologic section of a normal supraspinatus tendon insertion site demonstrates the four zones of a direct insertion: tendon (T), unmineralized fibrocartilage (U-Fc), mineralized fibrocartilage (M-Fc), and bone (B). (B) This histologic section of the tendon-bone attachment site 4 weeks after supraspinatus tendon repair in a rat model shows the site is characterized by a fibrovascular scar tissue interface (IF) without formation of an intermediate zone of fibrocartilage between tendon (T) and bone (B).