. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 66 ANNALS OF THE SOUTH AFRICAN MUSEUM Replacement of the Incisors In the premaxilla (fig. 7) a cavity develops in the bone lingually of the alveolus which houses each functional incisor. This cavity houses the germ from which the replacing incisor develops. By the time the replacing crown reaches a certain stage of development the inner or lingual wall of this cavity develops, by resorption of the bony tissue, a perforation. This opening enlarges to form a long oval fenestra and through this fenestra
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 66 ANNALS OF THE SOUTH AFRICAN MUSEUM Replacement of the Incisors In the premaxilla (fig. 7) a cavity develops in the bone lingually of the alveolus which houses each functional incisor. This cavity houses the germ from which the replacing incisor develops. By the time the replacing crown reaches a certain stage of development the inner or lingual wall of this cavity develops, by resorption of the bony tissue, a perforation. This opening enlarges to form a long oval fenestra and through this fenestra the crown of the replacing tooth Fig. 7. Jonkeria boonstrai. 9079 X J. Ventral view of upper jaws. emerges. As the replacing tooth continues its growth it moves labially into the lingual wall of the alveolus of the functional tooth which is gradually reabsorbed, until the new alveolus coalesces with the old alveolus. The old tooth has con- comitantly suffered resorption and as it disappears the new tooth takes over its alveolus. In the meantime the fenestra through which the replacing crown can first be seen has closed up from above downwards so that the new tooth when arriving in the old alveolus has its own lingual alveolar wall. The talon of the young tooth, when just emerging, is flattened antero-posteriorly, roughly triangular in outline with its inner face coarsely striate and since these striae extend to the edges these are Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original South African Museum. Cape Town : The Museum
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
