Skeletal maturation of the human fetus assessed radiographically on the basis of ossification sequences in the hand and foot

In studies of postnatal human development the skeletal maturation of the hand has been found to be a better indicator of general physical maturation than attained body height. For assessment of prenatal human development the Crown-rump length (CRL) has so far been the most commonly used measure. The object of the present study is to examine the possibility of also using the skeletal maturation of the hand as a maturity indicator in fetal development. The study is based upon a radiographic and histochemical investigation of 169 human fetuses. On the basis of counting silver-impregnated diaphyses on radiographs of the hand and foot a maturity indicator (CNO = Composite Number of Ossified bones in hand and foot) was established. Owing to the marked regularity of the recorded ossification pattern, the CNO parameter can be used for evaluating fetal maturation during the early half of the prenatal period. To supplement the assessment of skeletal maturation during the later stages of development, a classification based on the shape of some bones was included in the study. In many cases fetuses of the same size (CRL) exhibited different stages of skeletal maturation (CNO). In accordance with findings from assessment of postnatal development, a more accurate evaluation of fetal development is obtained by combining the size parameter CRL with an assessment of fetal skeletal maturation, CNO.     

GROWTH PATTERNS OF THRINAXODON LIORHINUS, A NON-MAMMALIAN CYNODONT FROM THE LOWER TRIASSIC OF SOUTH AFRICA

Abstract:  The growth dynamics of the Early Triassic non-mammalian cynodont Thrinaxodon liorhinus were assessed through bone histology. Several limb bones of various sizes were examined, revealing a rapidly deposited, uninterrupted, fibro-lamellar bone tissue. A region of slowly deposited parallel-fibred bone occurs peripherally in most skeletal elements studied, becoming more extensively developed in the larger limb bones. On the basis of the bone histology, it is proposed that Thrinaxodon liorhinus grew rapidly during early ontogeny, and at a slower rate with increasing age, possibly once sexual maturity was reached. Variation in bone tissue patterns at different stages of ontogeny is noted and discussed. Given that growth rings are generally absent from the skeletal elements studied, and that the environment was seasonal, it appears that Thrinaxodon liorhinus growth was unaffected by environmental fluctuations.     

Scoring system for estimating age in the foot skeleton

This study assesses chronological age of immature individuals from the degree of ossification evident in the foot skeleton. We considered all tarsal and ray bones in various combinations to determine the most sensitive indicators of chronological age. Skeletal maturity was rated according to a subjective but simple scoring system applied to radiographs of normal feet of children of known chronological age. Scales for assessing the primary center of ossification, secondary center of ossification, and state of fusion are defined. In general, as expected, females show earlier onset of skeletal maturity than males; in particular, females in our sample are skeletally mature in most elements beginning 48 months prior to the earliest incidence of skeletal maturity in males for the same bones. Females in our sample show a marked tendency toward skeletal maturity of all elements by 150 months of age, while males do not show the same tendency until approximately 200 months of age. In general within each sex, consecutive states of fusion show broad overlap in range of chronological age within each bone. Combining scores from several different bones enables a reasonable estimate of potential age in a test application of the model.     

Postnatal ontogeny, population structure, and extinction of the giant moa Dinornis

Recent reinterpretation of the giant moa Dinornis as consisting of two sexually dimorphic allospecies permits thorough site-by-site investigation of the ontogeny and population biology of this genus. Analysis of subadult skeletal material from natural swamp sites in the North and South Islands of New Zealand forms the basis for recognition of growth series for each long bone element, characterized by sequential formation of fossulae in the femur and fusion of bones in the tibiotarsus and tarsometatarsus. Femora reached progressive developmental stages more rapidly than the other long bones, but all three elements reached maturity at about the same time. Patterns of bone fusion in Dinornis are more similar to those in Apteryx than in Struthio, and kiwi are recognized as a suitable developmental analog for interpreting moa ontogeny. Samples from Bell Hill Vineyard Swamp (South Island) and Makirikiri swamp (North Island) are interpreted as representing autochthonous moa populations; comparison with stages of kiwi long bone development suggests that Dinornis at these sites had high adult survivorship in strongly K-selected populations, with 72.5-87.3% of individuals having achieved adult body mass, and 55.9-78.2% being sexually mature. The pattern of low fecundity and probable high longevity in both Dinornis species suggests that populations were vulnerable to loss of adults, primarily through hunting, rather than as a result of habitat destruction.     

The measurement of skeletal maturity

A new approach to the measurement of skeletal maturity has been described. This was applied to the distal end of the femur in boys aged one month to four years. It is planned to extend this study to girls and to other ages and sites and to other bones in the knee area. The study began with the testing of reported indicators of skeletal maturity in respect of replicability, validity, discrimination and universality. As a result, seven qualitative graded indicators and three quantitative ratios were selected for further investigation. Maturity scores based on each qualitative indicator can be estimated using parameters from a simple probit analysis with chronological age as the independent variable. The statistical factors that influence the usefulness of these indicators have been discussed. The quantitative indicators investigated appear very useful as measures of maturity although some are redundant. The planned extension of the present study should allow the formulation of an appropriate model for the measurement of skeletal maturity by combining qualitative and quantitative data.     

Ossification of the human fetal basicranium

Previous investigations of prenatal development of the human cranium have not identified the sequence of its ossification. The purpose of the present study was to elucidate the pattern of skeletal maturity of the cranial bones in the midsagittal region anterior to the foramen magnum. This study is based upon a radiographic and histochemical investigation of midsagittal tissue blocks of the cranial bases of 73 human fetuses derived from the first half of the prenatal period. A marked regularity in the ossification pattern of the bones in the midsagittal part of the human cranium was observed. Ossification starts in the frontal bone. The sequence in which the next bones ossify is occipital bone, basisphenoid bone, presphenoid bone, and ethmoid bone. The material was divided into 7 maturity stages devised for this analysis. The stages were related to general fetal size (crown-rump length) and to general fetal maturation (composite number of ossified bones in hand and foot). Skeletal development of the median part of the human cranium is not strictly correlated with the size or the stage of general maturation of the fetuses. Knowledge of normal skeletal development is necessary for understanding anomalies of development.     

Determination of sex and maturity stage of great sturgeon (Huso huso) using steroid sex hormones profiles,histology and laparoscopic images of gonads

We studied sex and maturity stage of great sturgeon with different reproductive stages using sex steroid hormones concentrations in blood plasma, gonad histology and laparoscopic technique. One hundred sixty farmed great sturgeons at ages between 1 and +12 years and weight ranged from 0.45 to 49.65 kg (80 males and 80 females, 20 fish of each maturity stage) were selected. Mean sex steroid levels showed that testosterone (T) and 11ketotestosterone (11KT) in plasma varied significantly by sex and maturity stage. But the mean concentrations of 17B‐estradiol (E2) varied significantly only between the maturity stages I and III. All fish were sex determined by laparoscopy and histology examinations confirmed it. Our results showed, however laparoscopy was effective method for sex determination at four maturity stages, but young fish at maturity stage I required gonadal histology examinations to confirm sex. The present study results showed that some steroid sex hormones (T and 11KT) can be used to determine sex and reproductive stage in great sturgeon, especially in later maturity stages. Although the laparoscopy may be stressful and cause small scars on the body of the fish, but it is a fast, effective, and cheap method for sex and maturity stage assessment (30 to 40 s for each fish), especially at later maturity stages. Histology of gonads is a very accurate, but it is an invasive method and not a suitable technique for commercial purposes. Histology is more suited for scientific studies than commercial application. The ability to use minimally invasive methods for sex determination will assist broodstock management and conservation in sturgeons.     

The variation of the cross-sectional shape in the long bones of birds and mammals

The transverse and sagittal diameters of the long bones were measured in a sample of 53 species of eutherian mammals and 36 species of birds. The scaling of the transverse and sagittal diameters of each bone to body mass was calculated. For each bone the ratio of sagittal/transverse diameter was calculated, as an expression of the cross-sectional shape of the bones. The distributions of the ratios were not significantly different from normality in all the avian bones and in the mammalian femur and tibia. In most cases, the mean of the distribution was significantly different from 1 (circular shape). The analysis shows that changes in the ratio can be caused by selective factors, considering the correlation predicted between the breaking moments and the radii, but at the same time the cross-sectional shape of mammalian and avian long bones may have a phylogenetic basis. Finally, the previous assumption of relationship between bone curvature and stress predictability, is also discussed.     

西北印度洋鸢乌贼角质颚外形变化的影响因素

根据2019年冬春季(2—5月)中国灯光罩网渔船在西北印度洋生产调查期间采集的1009尾鸢乌贼样本,分析了其角质颚外部形态变化的影响因素。结果表明: 角质颚外形特征参数在不同性别、不同胴长组和不同性腺成熟度间均存在显著差异。胴长组201～250 mm以及雌性个体性腺成熟度Ⅱ期和雄性个体性腺成熟度Ⅲ期的各特征参数增幅达到峰值。除上翼长与上脊突长比值(UWL/UCL)和下头盖长与下脊突长比值(LHL/LCL)存在性别间显著差异外,其余特征参数与脊突长的比值均无性别间显著差异,各特征参数与脊突长的比值在不同性腺成熟度、不同胴长组间也无显著差异,比值保持稳定,表明角质颚各区域生长保持一致。研究表明,201～250 mm可能是西北印度洋鸢乌贼角质颚外部形态在胴长上的生长拐点,雌性个体性腺成熟度Ⅱ期和雄性个体性腺成熟度Ⅲ期可能对应角质颚外部形态在性腺成熟度上的生长拐点。     

Relative dental maturity and associated skeletal maturity in prehistoric native Americans of the Ohio valley area

Estimation of age-at-death of subadults in prehistoric skeletal samples based on modern reference standards rests on a number of assumptions of which many are untestable. If these assumptions are not met error of unknown magnitude and direction will be introduced to the subadult age estimates. This situation suggests that an independent estimate or estimates of age-related features, free of most of the assumptions made when using modern reference standards may be useful supplements in evaluating the age of subadults in prehistoric samples. The present study provides an internally consistent, population-specific measure of maturity for prehistoric Ohio valley Native Americans based on the seriation of dental development that may be used as a supplement to age-estimation. The developing dentition of 581 subadults from eight Ohio valley prehistoric-protohistoric groups was seriated within and among individuals resulting in a sequence of tooth development and a sequence of individuals from least to most mature. Dental maturity stages or sorting categories were then defined based on exclusive, easily observable, and highly repeatable tooth-formation stages. Tooth eruption (into occlusion), bone lengths, and fusion of skeletal elements are summarized by dental maturity stage. This procedure provides maturity estimates for skeletal features ordered by dental maturity stages derived from the same sample thus making explicit the relationship between dental and skeletal maturity.     

X射线衍射技术在烧骨实验研究中的初步应用

烧骨作为考古遗址中较为常见的一类特征遗物,对研究古人类用火行为有着重要的意义。过往研究表明,骨骼在加热过程中,其内部晶体会根据加热程度的不同产生不同的变化。骨骼在加热前的状态,能够在一定程度上反映古人类对骨骼进行热处理的动机与目的。为了了解骨骼在焚烧前的初始状态是否会对其内部晶体产生不同的影响,本研究利用56件现生羊骨进行了烧骨实验。实验设置了带肉骨、剔肉骨和干骨三种不同初始状态的骨骼,并在前人的研究基础上进一步细化了焚烧温度和时间参数。焚烧完成后,利用X射线衍射技术对所有样品进行了分析并观察其衍射图的差异。实验结果显示,骨骼有机质含量的多少,骨骼内部元素的不同,在一定的温度和时间条件下,会对骨骼内晶体的形成产生不同的影响。文章最后探讨了这种差异在考古研究中运用的可能性。     

Ultrastructure of spermiogenesis and spermatozoa in Diurodrilus subterraneus (Polychaeta,Diurodrilidae)

Spermiogenesis in the polychaete species Diurodrilus subterraneus may be divided into six stages. These stages, as well as the ultrastructure of the mature spermatozoa, are described based on TEM studies. The spermatozoa are unusual in having a very large acrosome followed by a region containing the nucleus and several ovoid mitochondria. A secondary acrosomal membrane forms a manchette around the nucleus and mitochondria. In this region, the plasma membrane is modified, with many small, mushroom-shaped cytoplasmic processes, each including filaments. The flagellum may be divided into three sequential regions; the longest, middle one is covered by a helically arranged mucous coat. Spermatozoa of the type described here are unknown among polychaetes but show certain superficial resemblances to those in oligochaetes. The resemblance of the mushroom-shaped bodies to spermatozoal microvilli in certain gnathostomulids is discussed. The phylogenetic relationships of Diurodrilidae are considered on the basis of this new information.     

Testes development and maturity classification of albacore (Thunnus alalunga ( Bonaterre, 1788)) from the Eastern Mediterranean Sea

The criteria of testicular maturity during the spawning season and for maturity rates are described according to age for 140 male albacore (Thunnus alalunga, Bonnaterre, 1788) sampled between April and August, 2002–2008 in the Eastern Mediterranean Sea. Histology of gonad samples was used to determine maturity status. Spermatogenesis and its relation to reproductive biology are reported. Fish ranged in fork length (FL) from 63 to 90 cm. The reproductive classes were based upon changes in the testicular morphology and stages of the germinative cells, i.e. immature, developing, maturing, spawning, and spent. Mature stages of testes including the smallest sample of a 63 cm male were observed from May to August of each year during the study. The reported evidence indicates that the size and age of first sexual maturity values of males of the Eastern Mediterranean population are nearly the same as in the Western Mediterranean population, but lower than in the Atlantic stock. The results of this histological investigation, conducted for the first time on this species in the Mediterranean Sea, will enable more precise future estimations for sustainability of the male albacore stock in the Eastern Mediterranean.     

Use of the Greulich-Pyle "Atlas of Skeletal Development of the Hand and Wrist" in a clinical context

Assessments of the relative maturity of individual children have been widely used to improve estimations of future growth as well as in evaluations of physiological disorders. Skeletal age (Hand) has been the most commonly used method for these estimations. In the clinical use of skeletal ages, certain problems are inherent regardless of which standard is selected. One of these is the method of reporting so that the cliniciam may learn of the normal variation at each age as well as the operational error of the specific assessor. Another problem lies in the proper clinical interpretation to be put upon significantly variant skeletal age readings in infancy, in childhood, or in adolescence. A third problem arises in limiting the use of skeletal ages which are read from areas which are involved with osseous pathology. And fourthly, a child's level of maturity is not static throughout his growing years; even with no change in therapeutic regime, marked shifts in relative maturity have been often noted. The wealth of experience which has now been acquired with the Greulich-Pyle standard is not the least of the advantages in using the Hand for the assessment of skeletal age. The 30 centers in this small area of the body, however, may be harmonious in development or may vary in “maturity” by as much as three years in a single hand. The problems then are: Which centers best represent the individual child? Which centers are most closely related to growth? Is growth in the hand and accurate index of the growth in other areas of the body? In total stature? The clinical assessment of future growth may best be made from a consideration of the whole child: his size, his physical characteristics, and his skeletal age, as well as the pattern of change-with-age in each of these. These problems will be discussed with illustrations drawn from the longitudinal Growth Study at this institution.     

Embryonic development of Python sebae - I: Staging criteria and macroscopic skeletal morphogenesis of the head and limbs

This study explores the post-ovipositional craniofacial development of the African Rock Python (Python sebae). We first describe a staging system based on external characteristics and next use whole-mount skeletal staining supplemented with Computed tomography (CT) scanning to examine skeletal development. Our results show that python embryos are in early stages of organogenesis at the time of laying, with separate facial prominences and pharyngeal clefts still visible. Limb buds are also visible. By 11 days (stage 3), the chondrocranium is nearly fully formed; however, few intramembranous bones can be detected. One week later (stage 4), many of the intramembranous upper and lower jaw bones are visible but the calvaria are not present. Skeletal elements in the limbs also begin to form. Between stages 4 (day 18) and 7 (day 44), the complete set of intramembranous bones in the jaws and calvaria develops. Hindlimb development does not progress beyond stage 6 (33 days) and remains rudimentary throughout adult life. In contrast to other reptiles, there are two rows of teeth in the upper jaw. The outer tooth row is attached to the maxillary and premaxillary bones, whereas the inner row is attached to the pterygoid and palatine bones. Erupted teeth can be seen in whole-mount stage 10 specimens and are present in an unerupted, mineralized state at stage 7. Micro-CT analysis reveals that all the young membranous bones can be recognized even out of the context of the skull. These data demonstrate intrinsic patterning of the intramembranous bones, even though they form without a cartilaginous template. In addition, intramembranous bone morphology is established prior to muscle function, which can influence bone shape through differential force application. After careful staging, we conclude that python skeletal development occurs slowly enough to observe in good detail the early stages of craniofacial skeletogenesis. Thus, reptilian animal models will offer unique opportunities for understanding the early influences that contribute to perinatal bone shape.