A text-book of dental histology and embryology, including laboratory directions . r-ing in the mesodermal tissue of the jaw arches very early infetal life. The cellular elements are at first very closelyplaced and large, but they grow smaller and take on thetypical form of pulp cells as the intercellular substance isincreased. By the sixteenth week the dental papillae forthe temporary teeth are covered by a layer of tall columnarcells, which will begin the formation of dentine about thattime. After the beginning of dentine formation the trans-ition from the dental papillae to the dental pulp i
A text-book of dental histology and embryology, including laboratory directions . r-ing in the mesodermal tissue of the jaw arches very early infetal life. The cellular elements are at first very closelyplaced and large, but they grow smaller and take on thetypical form of pulp cells as the intercellular substance isincreased. By the sixteenth week the dental papillae forthe temporary teeth are covered by a layer of tall columnarcells, which will begin the formation of dentine about thattime. After the beginning of dentine formation the trans-ition from the dental papillae to the dental pulp is verygradual, and it would be impossible to draw any sharp lineof demarcation between them. 204 DENTAL PULP Structural Elements.—The structural elements of the den-tal pulp are: 1. Odontoblasts. 2. Connective-tissue cells. 3. Intercellular substance. 4. Bloodvessels. 5. Nerves. The Odontoblasts.—The odontoblasts are tall columnarcells which form the outer layer of the pulp adjacent to thedentine, and from which cytoplasmic fibrils extend into thedentinal tubules. Fig. 156. Odontoblasts and forming dentine: E, forming enamel; D, forming dentine; O,odontoblasts; Dp, body of dental papilla. (From photomicrograph by Rose.) The character of the odontoblasts changes very greatlywith the age of the tissue, and the activity of dentine forma-tion. While the primary dentine is being formed they aretall columnar cells, each containing a large oval nucleus, THE ODONTOBLASTS 205 JV rich in chromatin and located in the pulpal third of thecell. From the dentinal end of the cell cytoplasm is con-tinued, without any line of demarcation, into the dentinaltubule as the dentinal fibril. In some instances two fibrilsmay be sent from a single odontoblast. The character ofthe odontoblast is beautifully seen in Fig. 156, a photographby Professor Rose. Fig. 157 *;; .=4 * *%n 9ii40! - i *>V<&< .MM 1 Odontoblasts. The section cuts obliquely through the odontoblasts: F, fibrils;JV, nuclei of
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectteeth, bookyear1912
