Histology and periostin immunohistology of mouse Achilles tendon and its insertion into the calcaneus. The entire anatomical structure was removed from the animal, fixed with 4% paraformaldehyde overnight at 4°C, and subsequently decalcified with 16.8% EDTA for 7 days and then stored in 70% ethanol. After paraffin embedding, 5-μm sections were cut and parallel sections were stained. (A) HE stain, overview. An enlarged view is shown in (B). (B) Detailed view of tendon approaching the calcaneus. Dotted lines delineate bone from mineralized, calcified cartilage (cC) and from nonmineralized cartilage (C). Some representative tenocytes are indicated by white arrowheads. (C) Periostin staining. Positively stained, round cartilage cells and tenocytes are clearly visible. (D) Negative control without primary antibody. B, bone; cC, calcified cartilage; C, nonmineralized (fibro)cartilage; F, fibrocartilage; T, tendon. HE, hematoxylin and eosin. Color images available online at www.liebertpub.com/scd