Sexual dimorphism in bone growth as a function of body size in moderately malnourished Guatemalan preschool age children

The sexual dimorphism in second metacarpal bone growth was investigated in 710 malnourished Guatemalan children one to seven years old to determine if the sex differences seen are only the result of differences in stature and weight. The study sample was mixed-longitudinal and consisted of 1,586 annual examinations. Boys have greater mean stature, weight, periosteal diameter, medullary diameter and cortical area than girls the same age, while girls have greater age specific mean cortical thickness and percent cortical area than boys. When the effects of stature, weight and age are removed boys still have significantly larger periosteal and medullary diameters and less cortical thickness and percent cortical area than girls. These differences between boys and girls therefore cannot be explained by sex differences in body size. However, no sex differences in cortical area remain after accounting for differences in stature, weight and age.     

大连学生体质发育的研究

为了解大连地区城乡学生生长发育状况及其规律,采用人体测量学方法,调查测量了大连地区7—18岁3834（城市男630,城市女645,乡村男1285,乡村女1274）名汉族学生23项形态指标,并利用以往资料,研讨了大连学生主要形态指标的生长发育规律、生长发育趋势、性差和地区差别。结果表明：1生长发育特点：大连学生测量项目的均值随年龄的增长而增加,生长曲线呈上升趋势并且男女有交叉现象。2性差：大连学生各测量项目均有明显的性差,除女生青春期（10—12岁）外,在其他年龄组均为男生大于女生。3生长的长期变化：大连7—17岁男女学生26年来身高、体重、胸围有较大幅度的增长,其每10年平均增长值分别为2.52cm和1.92cm、4.05kg和2.39kg、1.77cm和1.38cm。4城乡差：大连男女学生身高、体重、胸围仍存在城乡差别。     

腊尔山区苗族学生头面部形态特征

本项目对1896例腊尔山区6~16岁苗族学生（男919例,女977例）进行了人体测量,测量了10项头面部形态指标,并根据公式计算13项头面部指数值。结果表明,苗族学生头面部各指标均值随年龄增长而增加,同年龄段头面部各指标均值男生一般高于女生,且多数年龄段差异有统计学意义;男性的头长宽的、形态面的、形态上面的、容貌面的、颧额宽的、容貌上面的和容貌上面高的指数以及女性的形态面的、形态上面的、容貌面的、颧下颌宽度的、容貌上面高的指数随年龄增长总体趋势是先增加后递减;男性头面高的以及女性的头长高的、头宽高的和头面宽的指数随年龄增长逐渐增加;男女性之间的头长高的、头宽高的和额顶宽的指数比较显示,多数年龄段差异有统计学意义;苗族学生头型以中头型、高头型、阔头型多见,面型以阔面型、阔上面型为主;相对于其他族群,腊尔山苗族男生面型短而宽,头型偏长,女生面型偏短,头型稍偏长而窄。腊尔山苗族学生头面部特征与融水苗族、土家族等族群较为接近,与哈萨克族、新乡汉族相距较远。     

Sexual dimorphism in mandibular growth of French-Canadian children 6 to 10 years of age

Polynomial regression is used to model the mandibular growth of 28 girls and 26 boys who were followed longitudinally from 6 to 10 years of age. The pooled-within individual designs indicate that ramus height follows a linear pattern of size increase; corpus and total mandibular lengths display curvilineal, decelerating, patterns of growth over the age range. Multivariate analyses of variance reveal significant sex differences in size, favoring boys, for the two length measures at 6 years of age. Growth velocity for corpus length is also significantly greater in boys than in girls. Sexual dimorphism in the growth of total mandibular length is more complex, including differences in velocity and deceleration. Ramus height shows no significant pattern of variation between boys and girls for either size or growth velocity.     

Variation in soft-tissue thicknesses on the human face and their relation to craniometric dimensions

The average thickness of soft tissues on parts of the face is known, but its variation has not been related to cranial morphology. To investigate this relationship, measurements of facial soft-tissue depths and craniometric dimensions were taken on adult, white Australian cadavers (17 male and 23 female). Significant correlations between many soft-tissue depths and craniometric dimensions were found, suggesting a relationship between the amount of soft tissue present on the face and the size of the underlying bony skeleton. Soft-tissue depths were highly positively correlated with each other; craniometric dimensions were correlated but to a lesser extent. Males had thicker soft tissues and larger craniometric dimensions than females; considerable overlap of ranges was also noted. Multiple regression analysis was used to produce equations predicting the soft-tissue depth at specified areas of the face from craniometric dimensions. A subsample of nine cadavers was examined for the effects of tissue embalming. Embalming caused significant initial increases in facial soft-tissue depths. Cadavers embalmed for less than 6 months had soft-tissue depths significantly greater than for fully embalmed cadavers. The evidence that facial soft-tissue thicknesses vary with craniofacial dimensions has implications for forensic identification, facial aesthetic surgery, and approximation of the facial features of extinct individuals.     

Gender-specific growth patterns of transversal body dimensions in Croatian children and youth (2 to 18 years of age)

In a cross-sectional study of growth, 5,260 healthy children of both sexes from Zagreb (Croatia) aged 2 to 18 years were measured. Six transversal body dimensions were studied: biacromial, transverse chest, antero-posterior chest, biiliocristal, bicondylar humerus and bicondylar femur diamters. A significant increase in body diameters has been observed until the age of 14 to 15 in girls and until the age of 16 in boys, showing that girls have a 1 to 2 years shorter period of growth. Compared to boys of the same age, they achieved larger amounts of final transversal bone size throughout the whole growth period. The most pronounced example was the knee diameter that in girls attained 95% of adult size as early as the age of 10. In both genders, the adult size is achieved earlier in widths of the extremities than in those of the trunk. The studied transversal body segments showed different growth dynamics, which is gender-specific. While sexual dimorphism in pelvic and shoulder diameters emerged with pubertal spurt, gender differences in chest and extremities' diameters started early in life. In all ages, boys had larger chest, elbow and knee diameters. In pubertal age boys gained a significantly larger biacromial diameter (from the age of 13 onwards), while girls exceeded them in biiliocristal diameter (from 10 to 14 years). The findings of gender differences were compared to those reported for other European populations and their growth patters were discussed comparing viewpoints.     

Gender-specific growth patterns for stature,sitting height and limbs length in Croatian children and youth (3 to 18 years of age)

In a cross-sectional study of growth, 5,155 children (2,591 females, 2,564 males) from the town of Zagreb (Croatia) were measured. Four traits of linear dimensionality (stature, sitting height, arm and leg lengths) were studied in the age span of 3 to 18 years. A significant average annual increase of all four anthropometric parameters were observed up to 14 and 15 years of age in girls and 16 years of age in boys, showing that girls had a shorter growing period. In the prepubertal period until 9 years of age, gender differences were negligible. At the age of 10, boys were overgrown by girls in all parameters due to the earlier onset of puberty in girls. The growth gains for girls, when compared with those for boys, show a different pattern across variables. The female growth advantage remained in a two years period for the limbs length, but in a three year period for stature and the longest, for 4 years, for sitting height. The male predominance in size had an onset at the age of 13 for the limbs and in the age of 14 for stature and sitting height. The patterns of sexual dimorphism in stature and sitting height during growing years are similar to those observed in other populations of Europe. Growth of Croatian children and youth is very similar to that of the tallest European populations.     

Developmental changes in the facial soft tissues

Short-base stereophotogrammetry was used to study differential growth and development of the soft tissues of the face. Thirteen facial parameters were measured at ages 9, 11, 13, 15, and 16 years on 170 facial contour maps selected from a mixed longitudinal study of 26 boys and 26 girls. Each parameter was measured three-dimensionally, and its developmental progress at the earlier stages was expressed as a percentage of its value at 16 years of age. Standing height development was assessed in the same way. Three parameters that measured soft tissues surrounding the eyes grew little but were very advanced in their development, following a "neural" pattern. The remaining facial parameters grew more but were less advanced, and standing height was least advanced. There appeared to be three separate patterns of development, "neural," "facial," and "skeletal." Girls were, in general, smaller than boys, but their development was more advanced when measured as a percentage of size at 16 years compared with boys.     

The relationship between cranial base and maxillo-facial morphology in Egyptian children

The aim of this study was to investigate the relationship between the cranial base and maxillo-facial morphology in Egyptian children. Data were obtained from 95 lateral cephalograms for 61 boys and 34 girls aged from 7.5 to 9.5 years with mean age 8.5 years. Eighteen linear and 14 angular measurements were derived from 40 landmarks and recorded from the standardized radiographs that were traced following methods formerly defined and described. A principal component analysis of linear and angular measurements showed that anterior and posterior cranial base lengths and cranial base angle were closely associated in different ways with different aspects of maxillo-facial morphology in both sexes. This was more pronounced in boys. A significant positive relationship was found between anterior cranial base length and most of the variables describing the maxillo-facial morphology in both sexes. Posterior cranial base length was significantly correlated to the facial depth. The cranial base angle showed a significant negative correlation with the antero-posterior position of maxilla and mandible (SNA=-0.34, SNB=-0.27 and ANB=-0.24). In conclusion, cranial base configuration plays an important role in maxillo-facial morphology.     

Scaling peak VO2 to body mass in young male and female distance runners.

This study examined age- and sex-associated variation in peak oxygen consumption (VO2) of young male and female distance runners from an allometric scaling perspective. Subjects were from two separate studies of 9- to 19-yr-old distance runners from the mid-Michigan area, one conducted between 1982 and 1986 (Young Runners Study I, YRS I) and the other in 1999-2000 (Young Runners Study II, YRS II). Data from 27 boys and 27 girls from YRS I and 48 boys and 22 girls from the YRS II were included, and a total of 139 and 108 measurements of body size and peak VO2 in boys and girls, respectively, were available. Subjects were divided into whole year age groups. A 2 x 9 (sex x age group) ANOVA was used to examine differences in peak VO2. Intraindividual ontogenetic allometric scaling was determined in 20 boys and 17 girls measured annually for 3-5 yr. Allometric scaling factors were calculated using linear regression of log-transformed data. Results indicated that 1) absolute peak VO2 increases with age in boys and girls, 2) relative peak VO2 (ml x kg(-1) x min(-1)) remains relatively stable in boys and in girls, 3) relative peak VO2 (ml x kg(-0.75) x min(-1)) increases throughout the age range in boys and increases in girls until age 15 yr, and 4) peak VO2 adjusted for body mass (ml/min) increases with age in boys and girls. The overall mean cross-sectional scaling factor was 1.01 +/- 0.03 (SE) in boys and 0.85 +/- 0.05 (SE) in girls. Significant age x sex interactions and significant scaling factors between sexes identify the progressive divergence of peak VO2 between adolescent male and female distance runners. Mean ontogenetic allometric scaling factors were 0.81 [0.71-0.92, 95% confidence interval (CI)] and 0.61 (0.50-0.72, 95% CI) in boys and girls, respectively (P = 0.002). There was considerable variation in individual scaling factors (0.51-1.31 and 0.28-0.90 in boys and girls, respectively). The results suggest that the interpretation of growth-related changes in peak VO2 of young distance runners is dependent upon the manner of expressing peak VO2 relative to body size and/or the statistical technique employed.     

Asynchronous dentofacial development and dental crowding: a cross-sectional study in a contemporary sample of children in France

Background

The causes of dental crowding are not fully understood, but it may result from an evolutionary trend towards reduced facial volume, without a proportional reduction in tooth sizes. Most previous studies conducted among modern humans have revealed a very low or non-existent correlation between tooth size and jaw size. Cross-comparison between dental age and facial skeletal age could help to provide better knowledge of the dynamic process of dental crowding. The primary objective of this research was to study the synchronism of dental maturation and skeletal facial growth in a sample of modern children living in France. The secondary objective was to assess the link between dentofacial asynchronism and dental crowding.

Results

The random sample comprised 28 subjects (16 girls, 12 boys). Mean chronological age was 13.5 years (±2.1; range 9.2–17.6). Mean dental age was 14.2 years (±2.8; range 7.5–17) and mean facial skeletal age was 12.8 years (±2.6, range 7–22). In the estimations of dental age and facial skeletal age, there was no evidence of systematic bias. There were 10 subjects (9 girls, 1 boy) with asynchronous dentofacial development. Finally, there were 13 subjects (8 girls, 5 boys) with dental crowding. A significant association was found between delayed facial skeletal growth/advanced dental maturation and dental crowding (P = 0.01).

Conclusions

Dental maturation and facial growth are not necessarily synchronous. Further understanding of the interactions between dental maturation and facial growth could have crucial implications in biological anthropology, as well as for the clinical practice of orthodontists. From an anthropological perspective, this study suggests that asynchronous dentofacial development could, at least partially, explain the frequency of dental crowding in modern populations.     

Analysis of the vertical facial form in patients with severe hypodontia

We examined the lateral cephalograms of Russian patients in the following categories: control with acceptable occlusions (group 1); severe hypodontia with absence of six or more teeth (group 2); and severe hypodontia associated with hypohidrotic ectodermal dysplasia (HED) (group 3). Analysis was in a cross-sectional manner, comparing dimensions at the start of the mixed dentition phase (age 6-10) and in the permanent dentition (age 12-18). The groups were matched for age and sex. Thirty-one hard- and soft-tissue landmarks were traced, and 35 linear, 19 angular, and 7 ratioed measurements were taken and compared, using analysis of variance to compare the means of each group. A reduced anterior face height was found in groups 2 and 3 as a consequence of a reduced anterior lower face height. In group 2 in the mixed dentition, the posterior face height was also reduced. The inclination of the mandible (相似文献   

Fetal growth: boys before girls

At term birth, boys are heavier than girls. This difference is thought to be generated in part by androgen action; its time course has not been deciphered. Androgen action may not only increase weight gain, but may also alter its time course. We have tested this hypothesis by examining the difference in gestational age of 281,894 boys and girls with weights between 500-4,749 g. The age at which children are born with a given weight was found to depend on gender: boys were consistently younger than girls (p < 0.001), the age difference being most pronounced in the lower birth weight classes. Thus, the gender difference in fetal growth appears to be rather pronounced before the third trimester and relatively less marked towards term. In conclusion, the male conceptus seems to grow not only more, but also earlier than the female. Hence, some critical time windows of development may be slightly different in boys and girls, and this phenomenon may be one of the bases for gender differences in the sensitivity to fetal programming. Copyrightz1999S. KargerAG,Basel     

A forty-five year investigation for secular changes in physical maturation

In a stable, economically- and educationally-privileged population of 180 subjects observed from birth to beyond the period of maximum growth in height, no secular changes toward larger size or earlier adolescence were observed between the earlier-born and later-born boys or girls of the Child Research Council study series. The mid-birthdate for the 45 years of data collection was January 1, 1940 for the girls and May 1, 1936 for the boys. With none of the mean differences significant at the 0.05 level of confidence, the earlier-born subjects were both slightly taller and heavier from birth and, for the girls, adolescence was slightly earlier. Forty pairs of like-sexed siblings were included in the data. Coefficients of correlation were statistically significant for birthweight and menarcheal ages for the sisters and for height and weight at the age of maximum increment of growth in height for both sexes. In 12 of the 16 pairs of sisters, the older menstruated at an earlier age than the younger.     

Sexual dimorphism in growth from 8 to 18 years

A mixed longitudinal study of growth and development has been conducted, centering on an analysis of differences based on sex between the ages of 8 and 18 years for a series of 12 anthropometric indicators. The sample consisted of 50 girls and 63 boys. Proceeding from the specific differences, the variables can be divided into four groups with identical structures of differences. The first group comprises measurements of body height, body mass, shoulder width and pelvic span, all of which have higher values in boys between 8 and 10 and between 14 and 18. Between the ages of 11 and 13 girls are taller, heavier, with broader shoulders and pelvises. The second group covers measurements of subcutaneous fat. which are higher for girls throughout the period under review. The third group of indicators comprises the diameters of the joints of the extremities, i.e. of elbows and knees. Throughout the period under observation, these measurements are higher in boys, with the absolute differences between the sexes being the same at the age of 8 and ten years later. The fourth group consists of circumferences measurements of the extremities. It was found that calf circumferences manifested a specific inversion of the curves between 14 and 15, with girls showing a larger calf circumference up to the age of 14, and boys from the age of 15. The effect of earlier onset of puberty in girls was found to be reflected only on the inversion of the curve flow of the variables from the first group.     

Vertical growth of the anterior face and cranium in inner city Negro children

A longitudinal cephalometric study was conducted on the vertical growth of the cranium and anterior face on 60 inner city American Negro children, an equal number of boys and girls from four to nine years. Three vertical measurements were used for the purpose of this study. The head height was measured from sellion to bregma, bony nasal height from nasion to anterior nasal spine, and lower facial height from anterior nasal spine and lower facial height from anterior nasal spine to menton. The data were analyzed at annual ages and observations made relative to the growth trends. The findings of this study were compared with those on Caucasian children. No significant statistical difference was found in the mean head (cranial vault) height between the Negro and Caucasian children. The mean bony nasal height expressed as a percentage of subnasal height was found to be less in the Negro children. The difference decreased with age. The annual increment of growth in head height was greater from four to seven years than from seven to nine years. The findings are considered to imply that severe malnutrition may influence child growth.