Crown Region Research Articles

Microstructure of matrix and mineral components of eggshells from White Leghorn chickens (Gallus gallus)

The avian eggshell is a composite structure of organic matrix and mineral (calcium carbonate) that is rapidly and sequentially fabricated in the oviduct in <24 hr. The eggshell is an excellent vehicle for the study of biomineralization processes and the role of the organic matrix in the mineral-matrix composite. The organic matrix components of eggshells from White Leghorn chickens (Gallus gallus) were examined by transmission electron microscopy (TEM) and optical microscopy. The mineral phase was analyzed by TEM, scanning electron microscopy (SEM), X-ray compositional microanalysis, and electron diffraction. Ultrastructural examination of the matrices within the calcified eggshell reveals a complex architecture that differs within each of the major zones of the eggshell: the shell membranes, the mammillary zone, the palisade region, and the cuticle. The mammillary layer consists of the calcium reserve assembly (CRA) and crown region, each with a unique substructure. TEM images show that the matrix of the CRA consists of a dense, flocculent material partially embedded within the outer shell membrane (a mostly noncalcified region of the shell). The mantle of the collagen fibers of the shell membranes is rich in polyanions (cuprolinic blue-positive), as is the CRA matrix. The CRA is capped by a centrally located calcium reserve body sac (CRB sac) that contains numerous 300-400 nm, electron-dense, spherical vesicles. Directly above the CRB sac is a zone of matrix consisting of stacks of interconnected vesicles (similar in morphology to CRA vesicles) that are interspersed with a granular material. The palisade region, the largest of the mineralized zones, contains hollow vesicles ∼450 nm (s.d. = 75 nm) in diameter, with a crescent-shaped, electron-dense fringe. An interconnecting matrix material is also found between the vesicles in the palisades region. The cuticle is composed of two layers, a mineralized inner layer and an outer layer consisting of only organic matrix. The bulk of the mineral within the eggshell is calcite, with small amounts of needlelike hydroxyapatite in the inner cuticle and occasionally, vaterite micro crystals found at the base of the palisade (cone) region. The well-crystallized calcite crystals within the palisade are columnar, typically ∼20 μm wide by 100-200 μm long; aside from numerous entrapped vesicles and occasional dislocations, they are relatively defect-free. The bulk of the matrix found in the palisade and crown regions are thought to be residual components of the rapid mineralization process. The unique matrix structure within the CRB corresponds to the region of preferentially solubilized calcite used by the developing embryo and the hydroxyapatite found in the inner cuticle may play a role in the cessation of mineral growth. © 1996 Wiley-Liss, Inc.

Microstructure of matrix and mineral components of eggshells from White Leghorn chickens (Gallus gallus).

The avian eggshell is a composite structure of organic matrix and mineral (calcium carbonate) that is rapidly and sequentially fabricated in the oviduct in <24 hr. The eggshell is an excellent vehicle for the study of biomineralization processes and the role of the organic matrix in the mineral-matrix composite. The organic matrix components of eggshells from White Leghorn chickens (Gallus gallus) were examined by transmission electron microscopy (TEM) and optical microscopy. The mineral phase was analyzed by TEM, scanning electron microscopy (SEM), X-ray compositional microanalysis, and electron diffraction. Ultrastructural examination of the matrices within the calcified eggshell reveals a complex architecture that differs within each of the major zones of the eggshell: the shell membranes, the mammillary zone, the palisade region, and the cuticle. The mammillary layer consists of the calcium reserve assembly (CRA) and crown region, each with a unique substructure. TEM images show that the matrix of the CRA consists of a dense, flocculent material partially embedded within the outer shell membrane (a mostly noncalcified region of the shell). The mantle of the collagen fibers of the shell membranes is rich in polyanions (cuprolinic blue-positive), as is the CRA matrix. The CRA is capped by a centrally located calcium reserve body sac (CRB sac) that contains numerous 300-400 nm, electron-dense, spherical vesicles. Directly above the CRB sac is a zone of matrix consisting of stacks of interconnected vesicles (similar in morphology to CRA vesicles) that are interspersed with a granular material. The palisade region, the largest of the mineralized zones, contains hollow vesicles ∼450 nm (s.d. = 75 nm) in diameter, with a crescent-shaped, electron-dense fringe. An interconnecting matrix material is also found between the vesicles in the palisades region. The cuticle is composed of two layers, a mineralized inner layer and an outer layer consisting of only organic matrix. The bulk of the mineral within the eggshell is calcite, with small amounts of needlelike hydroxyapatite in the inner cuticle and occasionally, vaterite micro crystals found at the base of the palisade (cone) region. The well-crystallized calcite crystals within the palisade are columnar, typically ∼20 μm wide by 100-200 μm long; aside from numerous entrapped vesicles and occasional dislocations, they are relatively defect-free. The bulk of the matrix found in the palisade and crown regions are thought to be residual components of the rapid mineralization process. The unique matrix structure within the CRB corresponds to the region of preferentially solubilized calcite used by the developing embryo and the hydroxyapatite found in the inner cuticle may play a role in the cessation of mineral growth. © 1996 Wiley-Liss, Inc.

Distribution and organization of peripheral capillaries in dental pulp and their relationship to odontoblasts

Background Developmental and chronological changes in the peripheral capillaries of the dental pulp and their relationship to odontoblasts during dentin formation has not been sufficiently detailed. This study aims to elucidate the morphological changes of the peripheral capillaries in relation to the life cycle of odontoblasts. Methods Peripheral capillaries of the dental pulp were examined in the labial region of rat incisors and in the crown region of rat molars by using light, transmission, and scanning electron microscopy. Results Before the start of dentin formation, continuous capillaries formed a coarse vascular network under the odontoblast layer. With the start of dentin deposition, capillaries began to invade into the odontoblast layer and finally located close to the predentin, where they formed a dense vascular network consisting of fenestrated capillaries. In the incisors, dentin was formed actively even near the incisal tip, and fenestrated capillaries continued to locate in the odontoblast layer. In the molars, however, the activity of dentin deposition gradually decreased with the advance of dentin formation, and the fenestrated capillaries altered to continuous capillaries and withdrew from the predentin border to the odontoblastic-pulpal border shortly before the cessation of active dentin deposition. Conclusions It is concluded that the changes in the peripheral capillaries are closely related to the secretory activity of the odontoblasts. To facilitate a rapid and sufficient supply of raw materials from the bloodstream to the calcifying front, peripheral capillaries first approach the odontoblasts, invade into the odontoblast layer close to the predentin with increases in density, and finally alter the endothelium from the continuous to the fenestrated type in compliance with the nutritional requirements of the odontoblasts, which lay down the dentin. When the activity of odontoblasts decreases, capillaries first alter the endothelium from the fenestrated to the continuous type, then retreat from the odontoblast layer, and finally locate below the odontoblast layer. © 1996 Wiley-Liss, Inc.

Distribution and organization of peripheral capillaries in dental pulp and their relationship to odontoblasts.

Developmental and chronological changes in the peripheral capillaries of the dental pulp and their relationship to odontoblasts during dentin formation has not been sufficiently detailed. This study aims to elucidate the morphological changes of the peripheral capillaries in relation to the life cycle of odontoblasts. Peripheral capillaries of the dental pulp were examined in the labial region of rat incisors and in the crown region of rat molars by using light, transmission, and scanning electron microscopy. Before the start of dentin formation, continuous capillaries formed a coarse vascular network under the odontoblast layer. With the start of dentin deposition, capillaries began to invade into the odontoblast layer and finally located close to the predentin, where they formed a dense vascular network consisting of fenestrated capillaries. In the incisors, dentin was formed actively even near the incisal tip, and fenestrated capillaries continued to locate in the odontoblast layer. In the molars, however, the activity of dentin deposition gradually decreased with the advance of dentin formation, and the fenestrated capillaries altered to continuous capillaries and withdrew from the predentin border to the odontoblastic-pulpal border shortly before the cessation of active dentin deposition. It is concluded that the changes in the peripheral capillaries are closely related to the secretory activity of the odontoblasts. To facilitate a rapid and sufficient supply of raw materials from the bloodstream to the calcifying front, peripheral capillaries first approach the odontoblasts, invade into the odontoblast layer close to the predentin with increases in density, and finally alter the endothelium from the continuous to the fenestrated type in compliance with the nutritional requirements of the odontoblasts, which lay down the dentin. When the activity of odontoblasts decreases, capillaries first alter the endothelium from the fenestrated to the continuous type, then retreat from the odontoblast layer, and finally locate below the odontoblast layer.

Site-directed mutagenesis of two conserved charged amino acids in the N-terminal region of α subunit of E. coli-F 0F 1

Two conserved charged amino acids of the N-terminal ‘crown’ region of the α subunit of E. coli-F 1, α-D36 and α-R40 were exchanged for chemically related ( α-D36→K, α-R40→K) of unrelated amino acids ( α-D36→K, α-R40→G), respectively, by employing oligonucleotide-directed mutagenesis. ATP formation and ATP hydrolyzing activity of isolated plasma membrane vesicles was strongly inhibited in mutant HS2 ( α-D36→K), but only slightly affected in the other mutants. The inhibition is not due to a lower content of F 0F 1 in HS2. In this mutant the extent of the proton gradient generated by ATP hydrolysis was more than 80% inhibited; in all other transformants much smaller effects were observed. The proton gradient established by NADH oxidation was 33% decreased in HS2, but was decreased to a lesser extent in all other mutants. After blockage of F 0 by DCCD treatment, the same NADH-induced proton gradient was obtained in all transformants including HS2. This and the fact that the activity of NADH oxidation was unchanged indicate increased proton leakiness of F 0F 1 carrying the α-D36 αK mutation. In F 1 α-D36 is located in a domain contacting the β subunit in the vicinity of the arginine β-R52. The effect of α-D36→K replacement on catalysis and coupling thus may be due to an electrostatic repulsive effect in the crown region which alters the α and β subunit interaction.

Effects of Competition on the Postfire Recovery of 2 Bunchgrass Species

The effect of competition on the postfire recovery of Festuca idahoensis Elmer and Agropyron spicatum (Pursh) Scrib &Smith, was examined under natural conditions. Thirty plants of each species were exposed to fire applied with a portable instrument system that allowed precise control of fire temperature and duration, so that all plants received statistically similar fire severity levels inside the meristematic crown region. Treated plants were subjected to different levels of competition by periodically removing all or part of the aerial biomass around a monitored bunchgrass plant. Soil water potential, soil temperatures, and plant productivity were determined at monthly intervals during the growing season for the different competition treatments. No significant mortality due to fire was observed for plants of either species. Although Festuca did show meristematic tissue damage after fire, regrowth that occurred within 15 days after fire was more rapid than for Agropyron. Only Agropyron plants without competition reached prefire productivity levels. Soil water potential was significantly more negative in plots with competition. Temperatures in the upper 10-cm of the soil profile were significantly higher in plots without competition. Competition reduced root production and also restricted aboveground productivity by approximately 70% for Agropyron and 115% for Festuca. The capacity of these species to survive fire appears to be related more to the micro-environmental conditions created following fire and to their capacity to compete for available soil water, than to the direct effects of fire on plant tissues.

White crown rot - a new disease of cereals

A new cereal disease was observed in central New South Wales in 1990 and 1991. The most characteristic symptoms were the formation of whiteheads and the presence of profuse white mycelium enveloping tiller bases in the crown region of infected wheat plants. Sometimes, black zone lines were present in the white mycelium. An unidentified sterile basidiomycete was consistently isolated from the tiller bases and shown to be the causal agent in pot and field experiments. The fungus was pathogenic to wheat, barley and triticale. The disease has been named ‘white crown rot’ to distinguish it from crown rot caused by Fusarium graminearum Group 1, which is renamed ‘Fusarium crown rot’.

Stem Allometry in a North Queensland Tropical Rainforest

The stem allometry (tree height versus stem diameter) of four tree species found in a North Queensland rainforest was examined. These species were dicotyledonous trees, two of which were classed as early successional species and two as later successional species. No significant differences (P > 0.05) were found in the stem allometry of dicoty¬ledonous trees of the same successional status. However, significant differences (P < 0.05) in stem allometry were found when comparing species of different successional status. Later successional species, but not early successional species, were found to be elastically similar to a theoretical buckling limit. The relationship between stability safety factors and tree height indicated that both early and later successional species have large buckling safety margins when of low stature. At medium statures (subcanopy), early successional species display a moderate buckling safety margin while later successional species exhibited their lowest buckling safety margin. At tall statures (canopy and above), early successional species exhibited their lowest buckling safety margin while later successional species had moderate buckling safety margins. Stem allometry may be influenced by a tree's life-span, wood density, and environmental conditions in its crown region.

Changes in radial increment in stems and roots of balsam fir [Abies balsamea (L.) Mill.] after defoliation spruce budworm

Radial increment along the stems and the root systems of 20 balsam fir (Abies balsamea Mill.) was analysed as an indicator of resource allocation after a spruce budworm outbreak. The trees were located in a natural forest, 130 km north of Lake Saint Jean (Québec) in the boreal forest zone. The dynamics of the forest were determined by fire and insect outbreaks. The 20 analysed firs showed clear signs of the last two spruce budworm outbreaks. Tree-ring width was reduced one year earlier in the crown region than at the stem base, and was more variable in the root system. Many tree-rings were missing at the stem base section and especially in the root system (2099 missing rings). Recovery started with a time delay of one year from the upper part of the crown and continued downwards in the stem. The roots and the crown recovered within a longer period. Key words: Abies balsamea, Choristoneura fumiferana, dendroecology, radial increment, root, spruce budworm

Dielectric spectroscopy analysis on the interfacial composition of non-ionic micellar solutions

By iterative use of a suitable mixture equation for the dielectric permittivity of heterogeneous systems we investigate C 12E 6 solutions as a function of the monomer concentrations and of the temperature at four different solvent compositions: 0, 2, 4 and 6 molar urea in water. With this methodology we obtain the permittivity of the micellar head group crown termination as a function of the hydrated volume of the monomer head group, composed in our case by 6 PEO (polyethylene oxide) units and by the interdigitated solvent molecules. Then the intercept between the dielectric behaviour as a function of the PEO molar concentration of the micellar crown region and of a solution of PEO-water-urea gives an estimate of the actual composition within the interface, at a fixed temperature and solvent composition. Our results suggest a temperature dependence of the degree of hydration at the micellar interface in pure water solution. With mixed water-urea solutions, cosolvent adsorbtion at the micellar interface is observed.

Posterior dental size reduction in hominids: The Atapuerca evidence

In order to reassess previous hypotheses concerning dental size reduction of the posterior teeth during Pleistocene human evolution, current fossil dental evidence is examined. This evidence includes the large sample of hominid teeth found in recent excavations (1984-1993) in the Sima de los Huesos Middle Pleistocene cave site of the Sierra de Atapuerca (Burgos, Spain). The lower fourth premolars and molars of the Atapuerca hominids, probably older than 300 Kyr, have dimensions similar to those of modern humans. Further, these hominids share the derived state of other features of the posterior teeth with modern humans, such as a similar relative molar size and frequent absence of the hypoconulid, thus suggesting a possible case of parallelism. We believe that dietary changes allowed size reduction of the posterior teeth during the Middle Pleistocene, and the present evidence suggests that the selective pressures that operated on the size variability of these teeth were less restrictive than what is assumed by previous models of dental reduction. Thus, the causal relationship between tooth size decrease and changes in food-preparation techniques during the Pleistocene should be reconsidered. Moreover, the present evidence indicates that the differential reduction of the molars cannot be explained in terms of restriction of available growth space. The molar crown area measurements of a modern human sample were also investigated. The results of this study, as well as previous similar analyses, suggest that a decrease of the rate of cell proliferation, which affected the later-forming crown regions to a greater extent, may be the biological process responsible for the general and differential dental size reduction that occurred during human evolution.

Odontoblast processes in dentin revealed by fluorescent Di-I.

There has been controversy about the length and structure of the odontoblast process within dentin since the earliest histologic studies of teeth. Our objective was to use the fluorescent carbocyanine dye Di-I combined with a new gelatin embedment procedure and confocal microscopy to determine the structure and extent of odontoblast processes in developing and mature rat teeth, injured rat molars, reparative dentin, and adult monkey teeth. We found that odontoblast processes do not extend into outer dentin or to the dentin-enamel junction except during early stages of development. Those in innervated regions of crown are long and straight, whereas those in roots are extensively branched and shorter. Cavity injury to crown dentin caused odontoblast fragments to be aspirated into outer dentin. In reparative dentin the odontoblast processes were branched and similar to those in roots. We used photoconversion and electron microscopy to show that Di-I fills the entire odontoblast after gelatin embedment, including the cytoplasm. This is a different type of carbocyanine staining from any previously reported, and it also stains other cells in adjacent hard tissues such as bone and cementum. The Di-I-gelatin method is a new way to use carbocyanine dyes. It has enabled us to solve a long-standing controversy about the histology of teeth, and it should be useful for many other studies of cell structure.

The Relative Sensitivity of Two Bunchgrass Species to Fire

The response of two bunchgrass species, Festuca idahoensis and Agropyron spicatum, to fire was examined under three levels of fire severity. The fire treatment was applied with an instrument system that allowed precise control over the intensity and duration of fire, and full documentation of the temperatures experienced in various regions of each plant during the fire and postfire cooling phases. A quantitative index of fire exposure, or severity, for each plant was obtained by integrating the temperature curve for the meristematic crown region over the fire and postfire cooling periods. No significant plant mortality was observed at any fire severity level. Although tissue damage in newly initiated culms was observed for Festuca, this did not significantly affect culm or biomass productivity. Culm production was initiated earlier and more rapidly in Festuca than Agropyron, and within 60 days after fire exposure the total number of culms produced in Festuca was nearly that of unburned plants. Above ground biomass for both species was significantly less than that of unburned plants at the end of this 60-day period. Agropyron exhibited significantly less culm and biomass production at a moderate fire severity, whereas high fire severity was required for this reduction in Festuca. Contrary to previous studies, Festuca thus appears less sensitive to fire injury than Agropyron.

Fecundity and Fertility of Rhynchophorus cruentatus (Coleoptera: Curculionidae)

The palmetto weevil (R. cruentatus F.) breeds in a variety of stressed or dying palms (Giblin-Davis & Howard 1988, 1989). These large (1.9 3.0 cm long) weevils are associated with the native cabbage palmetto, Sabal palmetto (Walter), in Florida (Woodruff 1967). Semiochemicals emanating from stressed or dying palms and male conspecifics (Weissling et al. 1992, 1993, 1994, Giblin-Davis et al. 1994) are attractive to R. cruentatus adults. Although not fully understood, mating apparently takes place on dying palms and females lay their eggs in the leaf bases or directly into the wounds of the host. Larvae develop primarily in the crown region but can occasionally be found in the stem tissue. Last instar larvae migrate to the fibrous stem periphery or petiolar bases and construct cocoons from fiber (Giblin-Davis & Howard 1988). Research on an improved method to culture R. cruentatus has required the collection of a large number of eggs to produce neonate larvae for evaluation of diets. Using pineapple, Anana comosus (L.), as an ovipositional substrate, Giblin-Davis et al. (1989) reported the mean lifetime fecundity of field-collected females as 26 ? 15 eggs per female. However, pineapple proved to be a difficult media to dissect for removal of eggs. More suitable ovipositional substrates were investigated and we found that apple (Pyrus malus L.) slices were easily dissected and were readily accepted by R. cruentatus females. Using apple slices, we reinvestigated the fecundity of R. cruentatus females and determined fertility. Cocoons were harvested in the field from infested palms or in the laboratory from sugarcane (Saccharum officinarum L.) stem (Giblin-Davis et al. 1989). Cocoons were placed individually in covered 100-ml plastic cups with moistened tissue paper (Giblin-Davis et al. 1989) and were stored at 29?C until adult emergence. One male and one female were placed in a 500-ml covered plastic container with moistened tissue. After 48-72 h, males were removed and a slice of apple ('Red Delicious') was added. Slices were thin (5-15 mm; 10-18 g wet weight), convex segments covered by peel. Females oviposit through the apple pulp and most eggs are found along the peel. All containers were placed in an environmental chamber at 290 C with a 13:11 (L:D) photoperiod. Apple slices were usually replaced every 1-3 days until female death. Slices removed from containers were carefully dissected and eggs were removed. This test was repeated five times with four or five females per test (22 females total). Data were converted to the number of eggs laid per female per week. In addition, the total number of eggs laid per female was determined. During two of the tests, eggs removed from apple slices were placed in 15 x 100 mm plastic petri dishes lined with watermoistened filter paper, sealed with parafilm, and placed in the environmental chamber. Neonate larvae were removed from each dish at daily intervals and the dish resealed until all eggs hatched or decomposed. For the first test, fertility was determined every one to three days for 45 d. During the second test, eggs were col-

Within-crown distribution of male and female cones on clonal Sitka spruce trees

The within-crown distribution of cones (strobili) was mapped on 48 mature grafts of Sitka spruce [Picea schensis (Bong.) Carr.]. The total number of cones per tree was increased by a mainstem injection of 20 mg GA4/7 and 8 mm wide bark ring. The cones and buds were classified as either lateral or terminal on each individual branch. The distribution of lateral female, terminal female, lateral male and terminal male cones, showed a general progression from the upper distal to lower proximal regions of the tree crown in all 12 clones. Evidence for preferential allocation of cones to particular branch types is presented. The region of the tree with the greates number of cones varied with treatment and reflected differences in the sex ratio of the individual trees. There is evidence for a relationship between branch length, position within the crown and the type of cone produced.

Interfacial conformation and composition of C 12E 6 micelle in water inferred by dielectric spectroscopy

An iterative use of a suitable mixture equation for dielectric permitivity of heterogeneous systems can give direct information on the permittivity of the micellar head group crown, composed in the present case of six PEO terminations and of interdigitated water molecules. The results obtained giving as a free parameter the actual conformation of the head group chains, i.e., the thickness of the micellar crown, l h, that defines the available volume for water molecules too. The dielectric behaviour of the crown region is compatred with that obtained from PEO-water mixtures to estimate the actual value of l h at each temperature. The number of interdigitated water molecules per PEO unit, n w, can then be extracted. The temperature dependence of l h and n w shows a saturation near the critical temperature.

Monoterpenes in Air Samples: European Intercomparison Experiments

Abstract An intercomparison experiment on preconcentration of monoterpenes from air samples was carried out by three European laboratories (Technische Universitat Munchen [TUM], Institut National Polytechnique de Toulouse [INP], Joint Research Center Isprs [JRC]) using Tenax porous polymer as an adsorbent. Sampling procedures, gas chromatographic analysis and standardisation methods differed in each laboratory and were compared in this study. Tenax adsorption tubes loaded with up to 10 monoterpenes (tricyclene, α-pinene, β-pinene, camphene, sabinene, myrcene, δ3-carene, p-cymene, 1,8-cineole and limonene) were created independently and exchanged for analysis between the working groups. For most monoterpenes the recoveries found by the different laboratories were 100%. The precision of analyses was better than 20%. Independent determinations of α-pinene mixing ratios in the air of the crown region in a natural spruce stand corresponded satisfactorily. Monoterpene emission rates of attached twigs in the sun...

New Nodulating Legumes of Potential Agricultural and Forestry Value from Subtropical Himalayan Ecosystems

ABSTRACT Legume species inhabiting a subtropical Himalayan sal forest ecosystem of the Dehra Dun Valley were evaluated for nodulation, with the objective of identifying potential legume-Rhizobium associations for enhancing soil fertility, agriculture and agroforestry of marginal lands. Four new nodulating legumes have been reported. All the four legume species are perennials and coppice well. Crotalaria calycina, Desmodium triquetrum subsp. pseudotriquetrum and Flemingia chappar are excellent fodder crops and efficient soil binders; these species are useful in the reclamation of acidic soils. Sophora mollis is a shrub to medium-sized tree and is used for both fodder and firewood; it can be used in the reclamation of alkaline soils. All the species had nodules on the crown region of the primary root, and the presence of copious leghaemoglobin in them suggests the effective nodulation of all the four species investigated. The nodules of Crotalaria were elongated and often forked, whereas in all other specie...

Sampling water from alfalfa (Medicago sativa) for analysis of stable isotopes of water

Abstract The isotopic composition of water extracted from various parts of alfalfa (Medicago saliva) plants was compared with that transpired by the plants to validate water extraction procedures, and to define the degree of alteration of the isotopic composition of water that occurred in different plant parts. The mean δ2H and δ18O values of water extracted from the upper tap root and lower crown regions were < 1‰ and 0.3‰ different from that of water transpired, respectively, with an analytical precision similar to that found in previous studies on soils and trees. Water from other plant parts closer to the leaves was enriched in 2H (up to 12.6 in upper stems) and 18O (4.2‰) with respect to that transpired. The enrichment was associated with a greater variability in δ2H values between replicate plants. δ2H‐δ18O data indicated that the isotopic enrichment was due to evaporation during transpiration. The study showed that azeotropic distillation is an accurate means of extracting water from alfalfa, altho...

ИЗМЕНЧИВОСТЬ РАЗМЕРОВ МОЛЯРОВ ВЕРХНЕЙ ЧЕЛЮСТИ НАСЕЛЕНИЯ ГОРОДА КРАСНОЯРСКА С УЧЁТОМ ВЕКТОРА ВРЕМЕНИ

The article presents the results of the study of odontology of the population characteristics in Krasnoyarsk city of XVII-XXI centuries. The aim of this work is to study the main variability dimensions of the molars of the right upper jaw of the population in Krasnoyarsk city in different time frames. For each object of the study, a map of the odontological examination was completed, including the measurement of the mesiodistal and vestibulooral diameters of the right upper jaw molars in the neck and crown regions of the tooth. Based on the results of the measurements, a comparison was made between the average size of the maxilla molars in the population of the city of Krasnoyarsk, depending on gender and the historical period. 131 skulls from osteological series of necropolises ofKrasnoyarsk (73 skulls - Pokrovsky necropolis, XVII-XVIII centuries, 58 skulls - Vsekhsvyatskiy necropolis, XVIII-XIX centuries) and dento-maxillary system of the modern population (68 people) were studied. A biometric study of the size of the molars of the right upper jaw has shown that over the past centuries, residents of the city of Krasnoyarsk experienced an increase in mesiodistal and vestibulo-oral teeth sizes in both men and women. A statistically significant increase in the mesiodistal diameter of the crown and neck of the 16th and 17th teeth was found in all groups of subjects, a statistically significant change in the vestibulooral size was characteristic only of the crown of the first molar of women.