koski1968 BAUME

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Volume 54Number 8Cranial growth centers 575Fig. 10. The condyle of a Sday-old rat. There is a relatively wide intermediate layer (theupper third of the nonossified top of the condyle, excluding the narrow darkly stained articularzone), a narrow zone of cartilage cells, and a wide zone of hypertrophic cells (darklystained). Note the absence of a structural organization, as seen in the epiphyseal growthplate in Fig. 1. (Courtesy of Dr. 0. Ronning.)dible. It is not an articular cartilage, nor is it an epiphyseal growth plate(Fig. 10). It does not even form from the same embryonic precursor tissue asthe epiphyseal cartilages,53 36 a fact which may have something to do with itsstructure and function.It is claimed that the condylar cartilage grows not interstitially, like theepiphyseal cartilages, but appositionally from the deepest layer of the connectivetissue cover of the condyle.82~ 83185l 86p 9o Th’ is mitotic layer responsible for theincrease of the cartilage is also called the intermediate layer. It is located betweenthe surface of the condyle and the cartilaginous portion of it,12 and thecells of this layer are not cartilage cells but are rather like undifferentiatedmesenchymal cells.7o In the epiphyseal cartilages, as we know, the proliferatingcells are cartilage cells. There are other differences between the condylar cartilageand the epiphyseal growth cartilages. The structural organization presentin the epiphyseal growth apparatuses is lacking in the condylar cartilage, andthe zone of nonhypertrophic cartilage cells in the condyle is very narrow, theforming cartilage cells turning hypertrophic almost immediately,12> 7o as in theclavic1e.l It is of special interest that the whole hypertrophic area in the condylarcartilage seems to be in a state of mineralization, whereas in the epiphy-
576 KoskiFig. 11. Two subcutaneous transplants of thr c~~ndplar wrl ilag~: proper, originally from a3.day-old rat, after 30 days of transplantal ion. Both spwimws aw ljartly raytilaginous, butchondroid bone formation is also soen, oq~wially in the larger qwcirncbn. Thv smaller one isof the original size, and the larger ant> appcaw lo Imw incwnswl in sizc in :i direction correspondingto the sagit,tal dimension in sit,,.Fig.fromcondj12. A subcutaneous transplant of the condylar cartilage plusa 5-day-old rat, after 30 days of transplantation. There is a mde in situ.adjacent ossified r amusoderate resemblance to a
Page 1 and 2: Cranial growth centers:Facts or f a
Page 3 and 4: 5 68 KoskiFig. 2. A schematic illus
Page 5 and 6: * kFig. 4. A schematic illustration
Page 7 and 8: Fig. 7. No growth is evident in :I
Page 9: the operations may dust as well b(:
Page 13 and 14: 578 Koskithe idea that the condylar
Page 15 and 16: Thcrc is, as TW have seen, much c~v
Page 17 and 18: 582 Koski48. Lacroix, I’.: The Or

koski1968 BAUME

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