Abstract
A study of the ultrastructure of the hypertrophic chondrocyte has been made possible by an improved method of fixation. In contrast to the general belief that the hypertrophic cells die, our results strongly suggest cell activity from the beginning of enlargement of the cell up to the stage where the lacuna breaks open. The sequence of alterations within the cell have been described, with the increase of endoplasmic reticulum contents, the appearance of many free ribosomes and the occurrence of electron-dense granules in the mitochondria as the most prominent characteristics. The possible functions of the cell have been discussed. Most interesting is the support for the hypothesis that hypertrophic chondrocytes may ultimately become bone cells.
Résumé
Une étude ultrastructurale de chondrocytes hypertrophiques est rendue possible par suite d'une meilleure méthode de fixation. Contrairement à l'opinion qui veut que les cellules hypertrophiques meurent, nos résultats suggèrent nettement une activité cellulaire allant du début de la croissance de la cellule au stade où la lacune s'ouvre. La séquence des altérations cellulaires est décrite, en allant de l'augmentation de l'ergastoplasme à la présence de ribosomes libres et de granules denses aux électrons dans les mitochondries. Les diverses fonctions possibles de la cellule sont décrites. Il est possible que les chondrocytes hypertrophiques se transforment en cellules osseuses.
Zusammenfassung
Eine verbesserte Fixationsmethode ermöglichte die Untersuchung der Feinstruktur des hypertrophischen Chondrocyten. Im Gegensatz zur allgemeinen Annahme, daß die hypertrophischen Zellen absterben, weisen unsere Resultate deutlich darauf hin, daß die Zellaktivität vom Moment der Zellvergrößerung bis zum Stadium, in welchem die Lacunen aufbrechen, vorhanden ist. Der Ablauf der Veränderungen innerhalb der Zelle wurde beschrieben, wobei die hervorstechendsten Charakteristika die Zunahme des endoplasmatischen Reticulums, das Auftreten von vielen freien Ribosomen und das Vorkommen von elektronenmikroskopisch dichten Granula in den Mitochondrien waren. Die möglichen Funktionen der Zelle wurde besprochen. Es ist äußerst interessant, daß dadurch die Hypothese, wonach die hypertrophischen Chondrocyten schließlich zu Knochenzellen werden, unterstützt wird.
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Holtrop, M.E. The ultrastructure of the epiphyseal plate. Calc. Tis Res. 9, 140–151 (1972). https://doi.org/10.1007/BF02061952
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DOI: https://doi.org/10.1007/BF02061952