Dental cosmos . ental sac; , epithelium of the jaw; , dental ridge; , labial furrow; ,ridge of the labial furrow ; L, lip. 100 diam. Drawn from a microphoto. tion of the star-like epithelial cells always takes place first in thecenter of the enamel-organ. The polyhedral cells of the rete muco-sum of Malpighi, which lie closely packed under the enamel-epithe- 1192 THE DENTAL COSMOS. Hum, increase here in size. The nuclei become somewhat larger, andmove apart from one another as the cell-bodies grow larger (Fig. 3,). Between these cells a clear protoplasmic fluid is secreted,ca
Dental cosmos . ental sac; , epithelium of the jaw; , dental ridge; , labial furrow; ,ridge of the labial furrow ; L, lip. 100 diam. Drawn from a microphoto. tion of the star-like epithelial cells always takes place first in thecenter of the enamel-organ. The polyhedral cells of the rete muco-sum of Malpighi, which lie closely packed under the enamel-epithe- 1192 THE DENTAL COSMOS. Hum, increase here in size. The nuclei become somewhat larger, andmove apart from one another as the cell-bodies grow larger (Fig. 3,). Between these cells a clear protoplasmic fluid is secreted,causing the appearance of small intercellular spaces. These spacesincrease, and press apart the neighboring cells to such an extent thatthe cells are finally connected with one another only by means of narrowprotoplasmic bridges (Fig. 4, ). Thus these transformed epithe-lial ceils appear star-like, and between them we find a wide-meshedcanal system, containing a thin fluid protoplasm, apparently highly Fig. Fig. 3.—Cows foetus (aYa. cm. long). First milk molar. P, double papilla of the dentinegerm ; , dental sac ; Z. w, so-called dental wall, characteristic of Ruminantia ; , unmodi-fied epithelium of the jaw ; , enamel epithelium ; , enamel-pulp. 200 diam. suitable for a rapid circulation of nutritive fluids. The enamel-pulphas reached the height of its development at the time when the firstdeposition of dentine and enamel takes place (Fig. 5). It degen-erates when the deposition of the enamel increases, and reaches, inthe direction of the root, only down to the future neck of the tooth,—, to the place where the deposition of the enamel ends. Hertwigsepithelial sheath, which goes on growing as matrix for the developingroot, consists only of fused external and internal enamel-epithelium,and it never contains star-like cells of the enamel-pulp. Therefrom it HISTOGENY AND HISTOLOGY OF BONY AND DENTAL TISSUES. II93 becomes evident that the development of t
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Keywords: ., bookauthor, bookcentury1800, bookdecade1890, booksubjectdentistry
