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. Author manuscript; available in PMC: 2018 Mar 30.
Published in final edited form as: Wiley Interdiscip Rev Dev Biol. 2016 Sep 1;6(1):10.1002/wdev.245. doi: 10.1002/wdev.245

FIGURE 1.

FIGURE 1

Histological features of joints. (a) Sutures are a type of immoveable articulation between bones, with the suture mesenchyme housing progenitors for bone growth and repair. Hematoxylin and eosin staining shows comparable coronal sutures of an E16.5 mouse embryo and young adult zebrafish. (b) The intervertebral discs of mouse and zebrafish have a very different structure. In mammals (shown here for postnatal Day 15 mouse), a cartilage endplate (CE) covers each vertebra, with the disc consisting of a ring of annulus fibrosus (AF) tissue and a core of nucleus pulposus (NP) tissue. In adult zebrafish, vertebral bones (red) are separated by layers of fat that appear white upon sectioning. (c) Synovial joints are freely moveable articulations characterized by fluid-filled cavities lined by articular hyaline cartilage. Some synovial joints, as shown in a section of the knee joint from an adult mouse, include additional specializations such as menisci (M). The adult zebrafish jaw joint has a clear articular cartilage (AC) layer and synovium (S) but no mensicus. Photos courtesy of Camilla Teng (A), Jennifer Zieba (B, mouse), and Denis Evseenko (C, mouse).