title: Structure, formation and role of cartilage canals in the developing bone.
abstract: In the long bones, endochondral bone formation proceeds via the development of a diaphyseal primary ossification centre (POC) and an epiphyseal secondary ossification centre (SOC). The growth plate, the essential structure for longitudinal bone growth, is located between these two sites of ossification. Basically, endochondral bone development depends upon neovascularization, and the early generation of vascularized cartilage canals is an initial event, clearly preceding the formation of the SOC. These canals form a discrete network within the cartilaginous epiphysis giving rise to the formation of the marrow space followed by the establishment of the SOC. These processes require excavation of the provisional cartilaginous matrix which is eventually replaced by permanent bone matrix. In this review, we discuss the formation of the cartilage canals and the importance of their cells in the ossification process. Special attention is paid to the enzymes required in disintegration of the cartilaginous matrix which, in turn, will allow for the invasion of new vessels. Furthermore, we show that the mesenchymal cells of the cartilage canals express bone-relevant proteins and transform into osteocytes. We conclude that the canals are essential for normal epiphyseal bone development, the establishment of the growth plate and ultimately longitudinal growth of the bones.
authors.affiliation: Department of Anatomy, Histology and Embryology, Division of Clinical and Functional Anatomy, Innsbruck Medical University, Müllerstrasse 59, Innsbruck, Austria. michael.blumer@i-med.ac.at
authors.forename: Michael J F
authors.initials: MJ
authors.lastname: Blumer
authors.forename: Stefano
authors.initials: S
authors.lastname: Longato
authors.forename: Helga
authors.initials: H
authors.lastname: Fritsch
mesh_terms: D000135:Acid Phosphatase / Q000235:genetics; D000818:Animals; D001846:Bone Development; D002356:Cartilage / Q000098:blood supply / Q000254:growth & development* / Q000502:physiology*; D010450:Endopeptidases / Q000235:genetics; D006132:Growth Plate / Q000502:physiology; D006801:Humans; D008322:Mammals; D045726:Metalloproteases / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics
chemical_list: D042461:Vascular Endothelial Growth Factor A; D000135:Acid Phosphatase; D010450:Endopeptidases; D045726:Metalloproteases; C083641:aggrecanase