Carpenter's principles of human physiology . a10CO3,6(PO4), 82-40 ; CaCl„, 0-23 ; MgHP04, 2*37;soluble salts, 035 ; organic substances,15-59 ; whilst to the dentine hegives the formula, based on Aebys «.analyses, of Ca10CO36(PO4), 72-06;§§|fMgHP04, 0-75; organic substances,27-70 = 100-51. In tracing the development of the \j!i <, ,teeth they are found to be essen- u \tially dermal structures, which have undergone calcification, the epitheliumforming the enamel, and the mucoustissue the dentine and cement. At thesixth week of foetal life a deep narrowgroove may be perceived in the upper Vert
Carpenter's principles of human physiology . a10CO3,6(PO4), 82-40 ; CaCl„, 0-23 ; MgHP04, 2*37;soluble salts, 035 ; organic substances,15-59 ; whilst to the dentine hegives the formula, based on Aebys «.analyses, of Ca10CO36(PO4), 72-06;§§|fMgHP04, 0-75; organic substances,27-70 = 100-51. In tracing the development of the \j!i <, ,teeth they are found to be essen- u \tially dermal structures, which have undergone calcification, the epitheliumforming the enamel, and the mucoustissue the dentine and cement. At thesixth week of foetal life a deep narrowgroove may be perceived in the upper VertleiJSect;,i: r„ l.„. „ , ,. jaw OI the human embryo, between about 2 inches long, showing the enamel germ, with the lip and the rudimentary palate. SafSSS?ftS2r tSSffSSifS This is speedily divided into tWO by a Palatal process, magnified 50 dlam. ridge, which afterwards becomes the external alveolar process; and it is inthe inner groove, which is termed the primitive dental groove, and is formed * Physiolog. Chemie, 1878, p. 56 CONNECTIVE TISSUES TEETH. Fig. 45. exclusively by a depression of the Malpighian layer, that the germs ofthe teeth subsequently appear. The groove is at first completely coveredas well as filled with the thickened epithelium of the oral cavity, so that on asurface view it is scarcely perceptible. From the bottom of the dentalgroove a narrow process of the oral epithelium dipsinto the subjacent mucous tissue, presenting on sec-tion the form of a short tubular gland (Fig. 44),but really constituting an epithelial fold along thewhole length of the jaw. As this fold deepens andenlarges a projection of the mucous tissue takesplace in the opposite direction (Fig. 45, /, 46, 5). Thisprojection or papilla is the tooth germ. By its growthit assumes the form of a club-shaped mass, and theenamel organ invests it like a cap. The first forma-tion of the dentine is effected by cells, termed odonto-blasts, which lie in the delicate connective tissue,ne
Size: 1733px × 1442px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectphysiology, bookyear1
