Figure 3

Anatomical locations of endochondral growth zones in human vs zebrafish. (A) Three synchondroses mediate growth of the human skull base (depicted in sagittal view): the spheno-ethmoidal-, intersphenoid- and spheno-occipital synchondroses. (B) Endochondral growth of human vertebrae and ribs (depicted in transverse view) takes place at neurocentral synchondroses and costochondral joints, respectively. (C) Over thirty endochondral growth zones mediate zebrafish pharyngeal skeleton growth. Three highly visible synchondroses mediate growth of first and second pharyngeal arch (PA1-2) skeletons. The PQ synchondrosis mediates growth of the QA and MP. The HS synchondrosis mediates growth of the SY and HM. The dorsal CH synchondrosis mediates growth of the CH and EH. In PA1 and 2, epiphyseal growth zones are found at the posterior MP, anterior SY, dorsal HM and anterior BH. In the gill supporting skeleton, epiphyseal growth zones are found at the ends of each CB and EB bone. (D) Axial growth of human stylopod (humerus, femur) and zeugopod (radius, ulna, tibia, fibula) bones is mediated by epiphyseal growth zones (=growth plates) located at each bone extremity. A single proximal epiphyseal growth zone mediates axial elongation of each autopod long bone (hand and foot phalanges). (E) In the zebrafish pectoral fin, epiphyseal growth zones are found at the distal end of each proximal radial. (F) In the zebrafish caudal fin, epiphyseal growth zones located at the distal end of each hypural bone (H1-5), the prehypural and two last haemal spines mediate axial elongation. AR, articular; BB, basibranchials; BH, basihyal; CB, ceratobranchial; CH, ceratohyal; DHH, dorsal hypohyal; EB, epibranchial; EH, epihyal; HM, hyomandibular; HS, hyosymplectic; IH, interhyal; MC, Meckel’s cartilage; MP, metapterygoid; PH, parhypural; PHB, pharyngobranchials; PL, pleurostyle; PT, palatine; QA, quadrate; RA, retroarticular; SY, symplectic; VHH, ventral hypohyal. Red indicates bidirectional- and blue indicates unidirectional growth zones.