Cells at the margins of a tendon explant, but not those inside the more densely packed, well-organized intact matrix, show propensity for differentiation to non-tendinous phenotypes.

Arrows indicate cells that are stained for markers of differentiation in adipogenic medium (Oil red O staining; row A) and osteogenic induction medium (Alizarin red S staining (row B). Images correspond to the edge of the sample, the middle of the explant section and in the endotenon (columns from left to right). Differentiated cells (black arrows) appear in the endotenon and peritenon, but not in the tendon core. Explants were analyzed from six different horses.