Discontinuities in the endothelium of epiphyseal cartilage canals and relevance to joint disease in foals

Hellings, Ingunn Risnes; Ekman, Stina; Hultenby, Kjell; Dolvik, N. I.; Olstad, Kristin

doi:10.1111/joa.12391

Cited by 14 publications

(29 citation statements)

References 47 publications

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“…The proportion of cartilage canals with an eosinophilic ring was similar to that in a study of the femur of foals (Hellings et al. ), thus the current study in the tarsus of a larger group of foals agrees with and confirms the previous observation found in the femur. A similar collagen ring was also found around epiphyseal cartilage canals on transmission electron microscopy (TEM) of sheep fetuses (Stockwell, ) and chicken embryos (Blumer et al.…”

Section: Discussionsupporting

confidence: 92%

“…The combined findings of the current, TEM (Hellings et al. ) and TPEF/SHG microscopy studies (Finnøy et al. ) suggest that the perivascular mesenchymal cells go through a fibroblast‐like stage while still located within cartilage canals, during which they may be capable of producing dense and tightly packed collagen consisting of collagen type I. Mesenchymal cells within cartilage canals have been shown to have chondro‐progenitor (Lutfi, 1970b) and osteo‐progenitor potential (Blumer et al.…”

Section: Discussionmentioning

confidence: 85%

“…In a previous TEM study of growth cartilage in foals, the flat, spindle‐shaped mesenchymal cells close to the exterior of the canals appeared to differentiate into chondroblasts and contribute to growth of the cartilage model (Hellings et al. ). Identical flat cells were identified on two‐photon‐excited fluorescent microscopy (TPEF) of porcine cartilage canals, and when combined with second harmonic generation (SHG) microscopy, it was possible to visualise production of collagen fibres by the flat cells (Finnøy et al.…”

Section: Discussionmentioning

confidence: 98%

“…() and Hellings et al. (). Individual cartilage canals as seen cut in transverse section were categorised as patent, early chondrifying or late chondrifying.…”

Section: Methodsmentioning

confidence: 98%

“…It was suggested that the collagen type I structure might add support to blood vessels within cartilage canals and that absence of the collagen ring could predispose individual canals to vascular failure (Hellings et al. ). This type of difference between individual canals warrants further study because it has the potential to explain why only some canals fail in osteochondrosis.…”

Section: Introductionmentioning

confidence: 99%

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Cartilage canals in the distal intermediate ridge of the tibia of fetuses and foals are surrounded by different types of collagen

et al. 2017

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Some epiphyseal growth cartilage canals are surrounded by a ring of hypereosinophilic matrix consisting of collagen type I. Absence of the collagen type I ring may predispose canal vessels to failure and osteochondrosis, which can lead to fragments in joints (osteochondrosis dissecans). It is not known whether the ring develops in response to programming or biomechanical force. The distribution that may reveal the function of the ring has only been described in the distal femur of a limited number of foals. It is also not known which cells are responsible for producing the collagen ring. The aims of the current study were to examine fetuses and foals to infer whether the ring forms in response to biomechanical force or programming, to describe distribution and to investigate which cell type produces the ring. The material consisted of 46 fetuses and foals from 293 days of gestation to 142 days old, of both sexes and different breeds, divided into three groups, designated the naïve group up to and including the day of birth, the adapting group from 2 days up to and including 14 days old, and the loaded group from 15 days and older. The distal tibia was sawn into parasagittal slabs and the cranial half of the central slab from the intermediate ridge was examined by light microscopy and immunohistochemical staining for collagen type I. Presence, completeness and location of the collagen ring was compared, as was the quantity of perivascular mesenchymal cells. An eosinophilic ring present on HE‐stained sections was seen in every single fetus and foal examined, which corresponded to collagen type I in immunostained sections. A higher proportion of cartilage canals were surrounded by an eosinophilic ring in the naïve and adapting groups at 73 and 76%, respectively, compared with the loaded group at 51%. When considering only patent canals, the proportion of canals with an eosinophilic ring was higher in the adapting and loaded than the naïve group of foals. The ring was present around 90 and 81% of patent canals in the deep and middle layers, respectively, compared with 58% in the superficial layer, and the ring was more often complete around deep compared with superficial canals. The ring was absent or partial around chondrifying canals. When an eosinophilic ring was present around patent canals, it was more common for the canal to contain one or more layers of perivascular mesenchymal cells rather than few to no layers. It was also more common for the collagen ring to be more complete around canals that contained many as opposed to few mesenchymal cells. In conclusion, the proportion of cartilage canals that had an eosinophilic ring was similar in all three groups of fetuses and foals, indicating that the presence of the collagen ring was mostly programmed, although some adaptation was evident. The ring was more often present around deep, compared with superficial canals, indicating a role in preparation for ossification. The collagen ring appeared to be produced by perivascular mesenchymal cells.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 98%

“…() and Hellings et al. (). Individual cartilage canals as seen cut in transverse section were categorised as patent, early chondrifying or late chondrifying.…”

Section: Methodsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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