The root is crucial for the physiological function of the tooth, and a healthy root allows an artificial crown to function as required clinically. Tooth crown development has been studied intensively during the last f...The root is crucial for the physiological function of the tooth, and a healthy root allows an artificial crown to function as required clinically. Tooth crown development has been studied intensively during the last few decades, but root development remains not well understood. Here we review the root development processes, including cell fate determination, induction of odontoblast and cementoblast differentiation, interaction of root epithelium and mesenchyme, and other molecular mechanisms. This review summarizes our current understanding of the signaling cascades and mechanisms involved in root development. It also sets the stage for de novo tooth regeneration.展开更多
Erianthus species are perennial C4 grasses with such high biomass productivity and high tolerance to environmental stresses that they can be grown in marginal land to supply raw material for cellulosic bioethanol. Bec...Erianthus species are perennial C4 grasses with such high biomass productivity and high tolerance to environmental stresses that they can be grown in marginal land to supply raw material for cellulosic bioethanol. Because high biomass production and strong tolerance to environmental stresses might be based on their large and deep-root system, we closely examined the morphology and anatomy of roots in first-year seedlings of field-grown Erianthus arundinaceus. The deep-root system of E. arundinaceus consists of many nodal roots growing with steep growth angles. Diameter of nodal roots with large variations (0.5 - 5 mm) correlates with the size and number of large xylem vessels. The microscopic observation shows that the nodal roots with dense root hairs developed soil sheath, hypodermis with lignified sclerenchyma in the outer cortex, and aerenchyma in the mid-cortex. In addition, starch grains were densely accumulated in the stele of nodal roots in winter. In the first year, E. arundinaceus developed less lateral roots than other reported grass species. The lateral roots formed a large xylem vessel in the center of the stele and no hypodermis in the outer cortex. Morphology and anatomy of E. arundinaceus root were discussed with reference to strong tolerance to environmental stresses.展开更多
Occlusion is commenced by contact of a tooth with an opposing tooth and is the mechanical force working against the periodontal ligament (PDL). Our recent study indicated that occlusion regulated tooth root elongation...Occlusion is commenced by contact of a tooth with an opposing tooth and is the mechanical force working against the periodontal ligament (PDL). Our recent study indicated that occlusion regulated tooth root elongation occurs during root development in rat molars. Using a non-occlusal model established to directly examine the effects of the absence of occlusion in developing first molars of upper jaw, histological analysis was performed to count the number of HERS cells, with Microarray used to analyse gene expression profiles. HERS cell numbers in normal molars decreased significantly more than those in experimental molars. In microarray data, a total of 59 genes showed significant differences (fold change > 2.0). Expressions of 55 genes in the experimental molars, which included PLAP-1/asporin and periostin, were significantly decreased than those in normal molars. These data indicate that occlusion during root development leads to a decrease in the number of HERS cells, and that the aforementioned genes may play an essential role in normal root formation.展开更多
基金supported by grants from the NIDCR, NIH (DE012711 and DE014078) to Yang ChaiNational Natural Science Foundation of China (81170943)+1 种基金Beijing Natural Science Foundation (7122051)Funding for Talents in Beijing (D) (2010D003034000012) to Xiao-Feng Huang
文摘The root is crucial for the physiological function of the tooth, and a healthy root allows an artificial crown to function as required clinically. Tooth crown development has been studied intensively during the last few decades, but root development remains not well understood. Here we review the root development processes, including cell fate determination, induction of odontoblast and cementoblast differentiation, interaction of root epithelium and mesenchyme, and other molecular mechanisms. This review summarizes our current understanding of the signaling cascades and mechanisms involved in root development. It also sets the stage for de novo tooth regeneration.
文摘Erianthus species are perennial C4 grasses with such high biomass productivity and high tolerance to environmental stresses that they can be grown in marginal land to supply raw material for cellulosic bioethanol. Because high biomass production and strong tolerance to environmental stresses might be based on their large and deep-root system, we closely examined the morphology and anatomy of roots in first-year seedlings of field-grown Erianthus arundinaceus. The deep-root system of E. arundinaceus consists of many nodal roots growing with steep growth angles. Diameter of nodal roots with large variations (0.5 - 5 mm) correlates with the size and number of large xylem vessels. The microscopic observation shows that the nodal roots with dense root hairs developed soil sheath, hypodermis with lignified sclerenchyma in the outer cortex, and aerenchyma in the mid-cortex. In addition, starch grains were densely accumulated in the stele of nodal roots in winter. In the first year, E. arundinaceus developed less lateral roots than other reported grass species. The lateral roots formed a large xylem vessel in the center of the stele and no hypodermis in the outer cortex. Morphology and anatomy of E. arundinaceus root were discussed with reference to strong tolerance to environmental stresses.
文摘Occlusion is commenced by contact of a tooth with an opposing tooth and is the mechanical force working against the periodontal ligament (PDL). Our recent study indicated that occlusion regulated tooth root elongation occurs during root development in rat molars. Using a non-occlusal model established to directly examine the effects of the absence of occlusion in developing first molars of upper jaw, histological analysis was performed to count the number of HERS cells, with Microarray used to analyse gene expression profiles. HERS cell numbers in normal molars decreased significantly more than those in experimental molars. In microarray data, a total of 59 genes showed significant differences (fold change > 2.0). Expressions of 55 genes in the experimental molars, which included PLAP-1/asporin and periostin, were significantly decreased than those in normal molars. These data indicate that occlusion during root development leads to a decrease in the number of HERS cells, and that the aforementioned genes may play an essential role in normal root formation.
