Vertical distribution of elements in cells and matrix of epiphyseal growth plate cartilage determined by quantitative electron probe analysis.

Abstract

Quantitative electron probe analysis was performed on chick epiphyseal growth cartilage prepared by two anhydrous methods, ultrathin cryosections and freeze-dried epoxy-embedded tissue. Levels of Na, Mg, P, S, Cl, K, and Ca were determined in cytoplasm, mitochondria, extracellular matrix, matrix vesicles, and mineral nodules in four zones of the cartilage--proliferative, prehypertrophic, early hypertrophic, and early calcification. The exceptionally high levels of Na and K (up to 550 and 200 mmol/kg wet wt, respectively) found in the matrix are believed to be largely bound to fixed anions. Within cells, Na was higher than K (140 versus 20-34 mmol/kg wet wt), a condition that may reflect hypoxia. Ca and P were low in cells and unmineralized matrix. Ca and P were high in mitochondrial granules of the early hypertrophic zone and diminished in amount in the calcifying zone; the converse occurred in matrix vesicles. Mg was low to undetectable except in heavily mineralized structures (i.e., mitochondrial granules, matrix vesicles, and mineral nodules). S levels were high in matrix (approximately 400 mmol/kg wet wt) and increased slightly with maturation. The amount of S present greatly exceeds Ca levels and implies that sulfate, the predominant form of sulfur in proteoglycans, may serve as an ion-exchange mechanism for the passage of Ca through the matrix to sites where Ca and phosphate are precipitated.

The process of calcification during development of the rat tracheal cartilage characterized by distribution of alkaline phosphatase activity and immunolocalization of types I and II collagens and glycosaminoglycans of proteoglycans

“…Previous in vitro studies have suggested that proteoglycan monomers and aggregates inhibit calcification or mineral formations of calcium and phosphate (Cuervo et al 1973;Blumenthal et al 1979;Chen et al 1984;Dziewiatkowsky and Majznerski 1985). On the other hand, other investigators have shown that there is no detectable drop in concentration of proteoglycans in the cartilage matrix of the growth plate which will calcify or has already calcified (Poole et al 1982a;Scherft and Moskalewski 1984;Hargest et al 1985;Poole et al 1989). Poole and co-workers demonstrated immunohistologically that the immunoreaction for proteoglycan monomer core protein and link protein even increased in the calcified cartilage (Poole et al 1982a).…”

Cartilage Oligomeric Matrix Protein Shows High Affinity Zinc-dependent Interaction with Triple Helical Collagen

“…However, little is known about the distribution in the different layers and compartments in cartilage. It has been demonstrated that the proportion of divalent cations vary between different layers in epiphyseal growth cartilage (49), scapular growth cartilage (52), and in adult articular cartilage (47). This distribution is likely to be influenced by the molecular composition of the ECM.…”

Comparison of the Ruthenium hexammine trichloride method to other methods of chemical fixation for preservation of avian physeal cartilage

“…Inclusions such as these have been reported in abnormal cartilage from humans (Hwang et al, 1982). Although there are no reports of similar inclusions observable by light microscopy in avian cartilage, dilated segments of rough endoplasmic reticulum have been observed ultrastructurally in avian physeal cartilage (Hargest et al, 1985a;Howlett, 1979;Kashiwa et al, 1975;Lutfi, 1974) and in murine cartilage (Schofield, 1975). A possible explanation for the lack of reports describing cytoplasmic inclusions at the light microscopical level in avian tissues is that they may have been overlooked.…”