Histopathology of tendinopathy

(A) Normal tendon. H&E.
(B) Increased tenocytes. H&E, patellar tendinopathy. Note the large increase in tenocyte numbers characteristic of healing tendon. The dense central structure represents a vessel wall.
(C) Increased proteoglycan. H&E, patellar tendinopathy. Increased blue-staining material surrounds an area of hypocellularity. These changes are typical of tendinopathy.
(D) Vascular hyperplasia. H&E, patellar tendinopathy. Large increase in microvessels is seen within the tendon substance. These changes are typical of tendinopathy.
(E) Collagen disorganization. H&E, patellar tendinopathy. Focal collagen remodeling.