The Role of Retinoic Acid in Establishing the Early Limb Bud

Retinoic acid (RA) was one of the first molecules in the modern era of experimental embryology to be shown capable of generating profound effects on limb development. In this review, we focus on the earliest events of limb development and specifically on the role of RA in establishing the domain of cells that will go on to form the limb itself. Although there is some consensus on the role of RA during the earliest stages of limb formation, some controversy remains on the mechanism of RA action and the requirement for RA signaling in forming the hindlimb buds.

Can Fetal Limb Soft Tissue Measurements in the Third Trimester Predict Neonatal Adiposity?

OBJECTIVES

Neonatal adiposity is associated with chronic metabolic sequelae such as diabetes and obesity. Identifying fetuses at risk for excess neonatal body fat may lead to research aimed at limiting nutritional excess in the prenatal period. We sought to determine whether fetal arm and leg soft tissue measurements at 28 weeks' gestation were predictive of neonatal percent body fat METHODS : In this prospective observational cohort study of singleton term pregnancies, we performed sonography at 28 and 36 weeks' gestation, including soft tissue measurements of the fetal arm and thigh (fractional limb volume and cross-sectional area). We estimated the neonatal body composition (percent body fat) using anthropometric measurements and air displacement plethysmography. We estimated Spearman correlations between sonographic findings and percent body fat and performed modeling to predict neonatal percent body fat using maternal characteristics and sonographic findings.

RESULTS

Our analysis of 44 women yielded a mean maternal age of 30 years, body mass index of 26 kg/m(2), and birth weight of 3382 g. Mean neonatal percent body fat was 8.1% by skin folds at birth and 12.2% by air displacement plethysmography 2 weeks after birth. Fractional thigh volume measurements at 28 weeks yielded the most accurate model for predicting neonatal percent body fat (R(2) = 0.697; P = .001), outperforming models that used abdominal circumference (R(2)= 0.516) and estimated fetal weight (R(2)= 0.489).

CONCLUSIONS

Soft tissue measurements of the fetal thigh at 28 weeks correlated better with neonatal percent body fat than currently used sonographic measurements. After validation in a larger cohort, our models may be useful for prenatal intervention strategies aimed at the prevention of excess fetal fat accretion and, potentially, optimization of long-term metabolic health.

A Novel Semiautomated Fractional Limb Volume Tool for Rapid and Reproducible Fetal Soft Tissue Assessment

The purpose of this study was to document the reproducibility and efficiency of a semiautomated image analysis tool that rapidly provides fetal fractional limb volume measurements. Fifty pregnant women underwent 3-dimensional sonographic examinations for fractional arm and thigh volumes at a mean menstrual age of 31.3 weeks. Manual and semiautomated fractional limb volume measurements were calculated, with the semiautomated measurements calculated by novel software (5D Limb Vol; Samsung Medison, Seoul, Korea). The software applies an image transformation method based on the major axis length, minor axis length, and limb center coordinates. A transformed image is used to perform a global optimization technique for determination of an optimal limb soft tissue boundary. Bland-Altman analysis defined bias with 95% limits of agreement (LOA) between methods, and timing differences between manual versus automated methods were compared by a paired t test. Bland-Altman analysis indicated an acceptable bias with 95% LOA between the manual and semiautomated methods: mean arm volume ± SD, 1.7% ± 4.6% (95% LOA, -7.3% to 10.7%); and mean thigh volume, 0.0% ± 3.8% (95% LOA, -7.5% to 7.5%). The computer-assisted software completed measurements about 5 times faster compared to manual tracings. In conclusion, semiautomated fractional limb volume measurements are significantly faster to calculate when compared to a manual procedure. These results are reproducible and are likely to reduce operator dependency. The addition of computer-assisted fractional limb volume to standard biometry may improve the precision of estimated fetal weight by adding a soft tissue component to the weight estimation process.

The clavicular part of the pectoralis major: a true entity of the upper limb on anatomical, phylogenetic, ontogenetic, functional and clinical bases. Case report and review of the literature

The pectoralis major consists of three parts: clavicular, sternocostal and abdominal. The first is usually separated from the deltoid by a deltopectoral triangular space, and often from the sternocostal part by another triangular space. The clavicular part is a new acquisition in Anthropoids, to optimize stabilization of the upper limb to the thorax thus permitting an increased limb mobility in Primates. It is synergetic with the deltoid in arm flexion and even more in adduction. This action is important in Humans, as the coracobrachialis becomes smaller in Mammals. Among non human Primates, those having cranially displaced shoulder joint show a significant clavicular origin of the pectoralis major. The clavicular origin might be necessary in flexion of the forelimb, when the humeral insertion of the muscle is on the same transverse plane as, or cranial to, the sternal manubrium. As to the blood and nerve supply, occurrence in Humans of a neuro-vascular pedicle for the clavicular part, shared with the deltoid, indicates a relatively morpho-functional independence of this part from the rest of the muscle. Under this regard, the width of the lateral pectoral nerve, which supplies the clavicular part of the muscle, may be related to a greater functional ability. Many manoeuvres for plastic and reconstructive surgery are performed by isolating the clavicular part of the pectoralis major. Indeed, this part may be considered as a true, self-standing anatomical entity. In fact, it has morphological individuality, peculiar bony attachments and functional autonomy, so that it is simply adjacent to the sternocostal part. Moreover, according to phylogenesis, this topographic relation develops secondarily, in parallel with the development of the clavicle. Therefore, it may be regarded not only as a simple part of an extrinsic muscle of the thorax, but also as an intrinsic muscle of the upper limb.

Prospective validation of fetal weight estimation using fractional limb volume

OBJECTIVES

To prospectively validate the use of fractional limb volume measurements for estimated fetal weight (EFW) during the second and third trimesters of pregnancy and to summarize the medical literature regarding application of fractional limb volume for fetal weight estimation.

METHODS

One hundred and sixty-four women prospectively underwent three-dimensional ultrasonography within 4 days of delivery. Birth weights (BWs) ranged from 390 to 5426 g. Fetal measurements were extracted using volume datasets for biparietal diameter, abdominal circumference, femur diaphysis length, fractional arm volume and fractional thigh volume. Fractional limb volumes were manually traced from a central portion of the humerus or femur diaphysis. Mean percentage differences and SDs of the percentage differences were calculated for EFW. The proportion of newborns with EFW within 5 or 10% of BW were compared with an estimate obtained using a Hadlock formula that was modified using model coefficients from the same local population sample.

RESULTS

Ultrasound scans were performed between 21.7 and 42 weeks' menstrual age. Optimal model performance (1.9 ± 6.6%) resulted from using a combination of biparietal diameter, abdominal circumference and fractional thigh volume. The precision of this model was superior to results obtained using a modified Hadlock model (1.1 ± 8.4%), although accuracy of these predictions was slightly decreased for female infants. For all fetuses, the prediction model that incorporated fractional thigh volume correctly classified a greater proportion of EFW within 5% (55.1 vs 43.7%; P = 0.03) or 10% (86.5 vs 75.9%; P < 0.05) of BW when compared with the modified Hadlock model.

CONCLUSIONS

Fractional thigh volume can be added to two-dimensional sonographic measurements of the head and trunk to improve the precision of fetal weight estimation. This approach permits the inclusion of soft tissue development as part of a weight estimation procedure for the assessment of generalized fetal nutritional status.

Soft tissue volume of upper arm in predicting small-for-gestational-age fetuses using three-dimensional ultrasound

PURPOSE

To assess the value of fetal soft tissue volume (STV) of the upper arm in predicting small-for-gestational-age (SGA) fetuses using three-dimensional (3D) ultrasound (US).

METHODS

We used 3D US to test the accuracy of fetal STV of the upper arm measurement in predicting SGA in a prospective cross-sectional study.

RESULTS

Fetal STV of the upper arm assessed by 3D US can differentiate SGA fetuses from appropriate-for-gestational-age (AGA) fetuses. Using the 5th percentile as the cutoff, the sensitivity of fetal upper arm STV in predicting SGA fetuses was 84.1%, specificity, 93.4%, positive predictive value, 71.1%, negative predictive value, 96.8%, and overall accuracy, 91.9%. In addition, the diagnostic accuracy of fetal arm STV was better than that of the biparietal diameter, abdominal circumference, and femur length.

CONCLUSION

Fetal STV of upper arm assessment by 3D US is a novel method to predict SGA fetuses.

New fetal weight estimation models using fractional limb volume

OBJECTIVES

The main goal of this study was to determine the accuracy and precision of new fetal weight estimation models, based on fractional limb volume and conventional two-dimensional (2D) sonographic measurements during the second and third trimesters of pregnancy.

METHODS

A prospective cross-sectional study of 271 fetuses was performed using three-dimensional ultrasonography to extract standard measurements-biparietal diameter (BPD), abdominal circumference (AC) and femoral diaphysis length (FDL)-plus fractional arm volume (AVol) and fractional thigh volume (TVol) within 4 days of delivery. Weighted multiple linear regression analysis was used to develop 'modified Hadlock' models and new models using transformed predictors that included soft tissue parameters for estimating birth weight. Estimated and observed birth weights were compared using mean percent difference (systematic weight estimation error) and the SD of the percent differences (random weight estimation error). The proportion of newborns with estimated birth weight within 5 or 10% of actual birth weight were compared using McNemar's test.

RESULTS

Birth weights in the study group ranged from 235 to 5790 g, with equal proportions of male and female infants. Six new fetal weight estimation models were compared with the results for modified Hadlock models with sample-specific coefficients. All the new models were very accurate, with mean percent differences that were not significantly different from zero. Model 3 (which used the natural logarithms of BPD, AC and AVol) and Model 6 (which used the natural logarithms of BPD, AC and TVol) provided the most precise weight estimations (random error = 6.6% of actual birth weight) as compared with 8.5% for the best original Hadlock model and 7.6% for a modified Hadlock model using sample-specific coefficients. Model 5 (which used the natural logarithms of AC and TVol) classified an additional 9.1% and 8.3% of the fetuses within 5% and 10% of actual birth weight and Model 6 classified an additional 7.3% and 4.1% of infants within 5% and 10% of actual birth weight.

CONCLUSION

The precision of fetal weight estimation can be improved by adding fractional limb volume measurements to conventional 2D biometry. New models that consider fractional limb volume may offer novel insight into the contribution of soft tissue development to weight estimation.

Fractional limb volume--a soft tissue parameter of fetal body composition: validation, technical considerations and normal ranges during pregnancy

OBJECTIVES

The main goals were to provide normal reference ranges for fractional limb volume as a new index of generalized fetal nutritional status, to evaluate the reproducibility of fractional fetal limb volume measurements during the second and third trimesters of pregnancy, and to demonstrate technical considerations for this technique.

METHODS

This was a prospective, cross-sectional study of gravid women during mid to late pregnancy. Fractional limb volumes were based on either 50% of humeral or femoral diaphysis length. Each partial volume was subdivided into five equidistant slices that were centered along the mid-arm or mid-thigh. Slices were traced manually to obtain fractional arm (AVol) or fractional thigh (TVol) volume. Reproducibility studies were performed, using Bland-Altman plots, to assess blinded interobserver and intraobserver measurement bias and agreement. Selected images were chosen to demonstrate technical factors for the acquisition and analysis of these parameters. Reference charts were established to describe normal ranges for AVol and TVol.

RESULTS

Three hundred and eighty-seven subjects were scanned to include 380 AVol (range, 1.1-68.3 mL) and 378 TVol (range 2.0-163.2 mL) measurements between 18.0 and 42.1 weeks' menstrual age. No gender differences were found in these soft tissue measurements (AVol, P = 0.90; TVol, P = 0.91; Mann-Whitney test). Intraobserver mean bias +/- SD and 95% limits of agreement (LOA) for fractional limb volumes were: 2.2 +/- 4.2% (95% LOA, - 6.0 to 10.5%) for AVol and 2.0 +/- 4.2% (95% LOA, - 6.3 to 10.3%) for TVol. Interobserver bias and agreement were - 1.9 +/- 4.9% (95% LOA, - 11.6 to 7.8%) for AVol and - 2.0 +/- 5.4% (95% LOA, - 12.5 to 8.6%) for TVol. Technical factors were related to image optimization, transducer pressure, fetal movement, soft tissue compression and amniotic fluid volume.

CONCLUSIONS

Fractional limb volume assessment may improve the detection and monitoring of malnourished fetuses because this soft tissue parameter can be obtained quickly and reproducibly during mid to late pregnancy. Careful attention should be placed on technical factors that can potentially affect optimal acquisition and analysis of these volume measurements.

Treatment of congenital upper extremity problems

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Describe the terminology and classification of congenital hand anomalies. 2. Describe the incidence and embryogenesis of some common congenital hand anomalies. 3. Discuss the general principles and goals for treatment of congenital hand anomalies. 4. Describe the management of five of the more common congenital hand anomalies (syndactyly, short digits, thumb duplication, hypoplastic thumb, and radial dysplasia).

SUMMARY

Congenital hand anomalies can cause substantial emotional and functional problems. This article reviews the etiology, classification, and management of some of the more common hand anomalies. A general approach to the patient and the goals of treatment are reviewed, as is the approach to five specific congenital hand anomalies: syndactyly, short digits, thumb duplication, hypoplastic thumb, and radial dysplasia.

Cartilage oligomeric matrix protein is involved in human limb development and in the pathogenesis of osteoarthritis

As a member of the thrombospondin gene family, cartilage oligomeric protein (COMP) is found mainly in the extracellular matrix often associated with cartilage tissue. COMP exhibits a wide binding repertoire and has been shown to be involved in the regulation of chondrogenesis in vitro. Not much is known about the role of COMP in human cartilage tissue in vivo. With the help of immunohistochemistry, Western blot, in situ hybridization, and real-time reverse transcription-polymerase chain reaction, we aimed to elucidate the role of COMP in human embryonic, adult healthy, and osteoarthritis (OA) cartilage tissue. COMP is present during the earliest stages of human limb maturation and is later found in regions where the joints develop. In healthy and diseased cartilage tissue, COMP is secreted by the chondrocytes and is often associated with the collagen fibers. In late stages of OA, five times the COMP mRNA is produced by chondrocytes found in an area adjacent to the main defect than in an area with macroscopically normal appearance. The results indicate that COMP might be involved in human limb development, is upregulated in OA, and due to its wide binding repertoire, could play a role in the pathogenesis of OA as a factor secreted by chondrocytes to ameliorate the matrix breakdown.

Observation of the relationship between the shape of skeletal muscles and their nerve distribution patterns: a transparent and microanatomic study

BACKGROUND

There are many gaps in the understanding of the neuroanatomy of skeletal muscles with regards to the nerve distribution pattern and shape of the muscles. This study was designed to examine the entire intramuscular nerve-distribution patterns of various human skeletal muscles.

METHODS

The relationships among nine skeletal muscles with various architecture (rhomboid major, biceps brachii, flexor pollicis longus, rectus femoris, sternohyoid, trapezius, masseter, digastric muscles) and their nerve-distribution patterns were investigated in four fetal cadavers using the Sihler staining method. The diameter and number of extramuscular (main) and major nerve branches, the number of minor nerve branches, and anastomoses were examined and evaluated statistically.

RESULTS

With regards to the number of extramuscular (main) nerve branches, the rhomboid major muscle resembled the flexor pollicis longus, trapezius, masseter, and sternohyoid muscles, and the anterior belly of the digastricus muscle (p > 0.05), whereas it was significantly different from the rectus femoris, the posterior belly of digastricus, and the long and short heads of the biceps brachii (p < 0.05). Trapezius and masseter muscles were different from all of the skeletal muscles that were studied with regards to the diameter of main branches (p < 0.05). The masseter muscle had the largest diameter (p < 0.05). With regards to the number of minor nerve branches, the sternohyoid muscle was significantly different from all the skeletal muscles that were studied (p < 0.05) except the short head of the biceps brachii, rectus femoris, and the posterior belly of digastricus (p > 0.05). As for the number of neural anastomoses, the sternohyoid muscle was statistically different from all skeletal muscles that were studied (p < 0.05) except the masseter and trapezius muscles (p > 0.005).

CONCLUSIONS

A surgeon's thorough knowledge of the relationship between the shape and nerve distribution pattern of skeletal muscles is important in successful reinnervation and regeneration of these muscles. It might also be useful in the field of muscle transplantation.

Fetal upper arm volume in predicting intrauterine growth restriction: a three-dimensional ultrasound study

As fetuses with intrauterine growth restriction (IUGR) may have increased risks with perinatal morbidity and mortality, prenatal diagnosis of IUGR is a very important issue in perinatology. To assess the efficacy of fetal upper arm volume in predicting IUGR, we undertook a prospective, cross-sectional study using quantitative three-dimensional (3D) ultrasound (US). In total, 40 fetuses with IUGR and 442 fetuses without IUGR were included for the upper arm volume assessment in utero by 3D US. All the fetuses were singletons and were followed up to delivery to establish whether they were complicated with IUGR or not. Our results showed that fetal upper arm volume assessed by 3D US can differentiate fetuses with IUGR from fetuses without IUGR well. The best predicting threshold for IUGR is at the 10th percentile by upper arm volume. Using the 10th percentile as the cutoff, the sensitivity of fetal upper arm volume in predicting IUGR was 97.5%, with specificity 92.8%, predictive value of positive test 54.9%, predictive value of negative test 99.8% and accuracy 93.1%. Furthermore, upper arm volume is the best parameter for detecting IUGR among the common fetal biometric indices, such as biparietal diameter (BPD), occipitofrontal diameter (OFD), head circumference (HC), abdominal circumference (AC), femur length (FL) and estimated fetal weight (EFW). In conclusion, fetal upper arm volume assessed by quantitative 3D US can be used to predict fetuses with IUGR antenatally. We believe fetal upper arm volume assessment by 3D US would be a useful test in detecting fetuses with IUGR.

The fetal arm: individualized growth assessment in normal pregnancies

OBJECTIVE

The goals were to introduce fractional arm volume (AVol) as a new soft tissue parameter of fetal growth assessment and to develop individualized growth standards, based on Rossavik models, for AVol, midarm circumference (ArmC), and humeral diaphysis length (HDL).

METHODS

A prospective longitudinal study of 22 fetuses was conducted using 2- and 3-dimensional sonography. Three new growth parameters (HDL, ArmC, and AVol) were used to establish individualized standards for arm growth with the use of Rossavik functions [P=c(t)k (+) s(t), where P is the anatomic parameter; c, k, and s are model coefficients; and t is the time variable]. Second-trimester models were specified from the linear slopes of growth curves before approximately 28.0 menstrual weeks. For a given fetus, normal third-trimester trajectories were predicted for each parameter. Observed and predicted measurements were compared by percent deviations.

RESULTS

Rossavik functions fit all parameter trajectories extremely well (R(2)=95.7%-99.4%). By fixing coefficients k at their mean values, their respective fits did not change, and the variabilities of both coefficients c and s were reduced. Coefficient c was also significantly related to second-trimester slope, as was s to c, for all 3 parameters (R(2)=97.7%-98.7%; P<.0001). Mean percent deviations between observed and predicted third-trimester HDL, ArmC, and AVol measurements were -0.1% +/- 2.9%, 0.5% +/- 4.6%, and 0.4% +/- 8.5%, respectively.

CONCLUSIONS

Individualized growth assessment, using HDL and ArmC, can accurately predict normal arm growth during the third trimester of pregnancy. AVol may also allow earlier detection and improved monitoring of soft tissue abnormalities that can occur in fetuses with growth disturbances.

Influence of breech presentation on the development of fetal arm posture

BACKGROUND

In previous research, an age-related developmental trend towards increasing arm flexion has been found for cephalic fetuses.

AIM

To determine if the development of arm posture in breech fetuses is comparable to that of cephalic ones.

SUBJECTS AND METHODS

Fetal arm posture was studied longitudinally by means of real-time ultrasound in 13 healthy breech and 10 healthy cephalic fetuses. Observations started from 33 weeks gestational age until birth and were performed weekly in the breech group and every 2 weeks in the cephalic group.

RESULTS

No difference could be found in arm posture between the left and the right arm in either group. Both breech and cephalic fetuses showed a clear preference for flexion in elbow and finger joints at all studied ages. After 36 weeks gestational age, the breech group showed significantly less wrist flexion when compared to the cephalic group (p = 0.037). A clear preference for location of the fetal hands near the fetal head could be observed for both groups.

CONCLUSIONS

As there is no evidence for an abnormal neuromotor development in healthy breech fetuses, the observed difference in wrist flexion is probably due to differences in intrauterine environment. Because of the preference for location of the hands in the vicinity of the fetal head, breech fetuses probably experience a less restricted environment (in the upper part of the uterus) than cephalic fetuses (in the lower part of the uterus).

Embryology of the upper limb: the molecular orchestration of morphogenesis

Accumulating data on the molecular interactions that occur during limb development have greatly enhanced our understanding of the process of limb morphogenesis. In this chapter, the key morphologic events are described, the broad categories of molecules involved are defined, the known molecular cascades and specific pathways that orchestrate limb development are reviewed. In addition, cascades disrupted by known genetic mutations associated with limb malformations are identified.

Anomalies of the forebrain with radial limb defects: Garcia-Lurie-Steinfeld syndrome?

BACKGROUND

Severe anomalies of the forebrain together with radial limb anomalies have been reported in Steinfeld syndrome, XK aprosencephaly, and partial monosomy 13q. Steinfeld syndrome is an extremely variable autosomal dominant condition that, in severe cases, is characterized by holoprosencephaly, radial limb defects, and renal and/or cardiac defects. In mild cases there may be only thumb hypoplasia, ocular coloboma, or oral clefts. XK aprosencephaly, also called Garcia-Lurie syndrome (GLS), is a usually sporadic disorder with radial limb defects and aprosencephaly/atelencephaly. Based on two atypical sibships, autosomal recessive inheritance has been suggested. Two patients with variations of monosomy 13q have been described with atelencephaly but, generally, Steinfeld and XK aprosencephaly patients are chromosomally normal. Holoprosencephaly in 13q deletion patients appears to be due to ZIC2 mutations, but ZIC2 has not been previously tested in Steinfeld syndrome or GLS patients.

CASES

We report three sporadic cases with clinical features intermediate between Steinfeld and GLS, including severe forebrain malformations and radial limb defects. All had normal karyotypes, and mutations in ZIC2 were absent in the two cases tested.

CONCLUSIONS

In our cases and in the literature there is significant clinical overlap between Steinfeld syndrome and GLS. We propose these conditions may not be nosologically or etiologically distinct. The spectrum of severe forebrain anomalies in these conditions is broader than previously thought and may include some neural tube defects. Mild cases are difficult to identify and the full range of expression remains unknown. Autosomal dominant inheritance with incomplete penetrance and frequent new mutations is postulated. Thorough clinical evaluation is recommended for children with severe forebrain and radial limb defects.

Congenital constriction band of the upper arm: the role of three-dimensional ultrasound in diagnosis, counseling and multidisciplinary consultation

Constriction band syndrome represents a sporadic condition that may result in amputations, constrictions and other deformities of the fetal limbs and body. Prenatal diagnosis by two-dimensional ultrasound has been reported. We present a case of constriction band involving the upper arm in which the assessment by three-dimensional ultrasound significantly contributed to the diagnosis and the multidisciplinary counseling. In fact, multiplanar imaging and surface rendering allowed a clear depiction of the extent of the constriction, the club-hand deformity and the relationship between the amniotic band, the cord and the fetal limb. This case represents a unique and effective application of three-dimensional ultrasound in prenatal diagnosis.

Unilateral transverse arm defect with subterminal digital nubbins

We present a case of unilateral terminal transverse forearm deficiency with subterminal digit-like nubbins, identified in a fetus from a pregnancy terminated electively in the second trimester because the distal right arm and hand could not be seen by ultrasound and were presumed to be absent. Pathologic evaluation showed distal transverse shortening, tapering to a point in the mid-forearm. Five primitive digital nubbins were present, located just proximal to the tapered point. The arm vessels appeared normal histologically, and the amnion showed no evidence of intrauterine disruption. Histologic examination of the nubbins revealed osteocartilaginous tissue, never described previously within digital nubbins. This fetus has the rare phenotype of terminal transverse limb defects with residual nubbins, but differs in that the nubbins are not at the tip of the terminal transverse limb defect.

Assessment of normal fetal upper arm volume by three-dimensional ultrasound

Fetal upper arm volume (UAV) is closely related to fetal growth and nutrition status. In the past, 2-D ultrasound (US) has shown limitations in assessing fetal UAV. With the recent advancement of 3-D US, the limitation in assessing fetal UAV by 2-D US can be overcome. To establish a reference chart of fetal UAV for clinical use, a prospective and cross-sectional study using 3-D US was undertaken to assess the fetal UAV in normal pregnancy. In total, 206 singleton fetuses ranging between 20 and 40 weeks of gestation that fit the criteria of normal pregnancies were enrolled in this study. Our results showed that fetal UAV is highly correlated with the gestational age. Furthermore, using gestational age (GA) as the independent variable and UAV as the dependent variable, the best-fit regression equation was UAV (mL) = 43.546 - 4.530 x GA + 0.133 x GA(2) (r = 0.913, n = 206, p < 0.0001). For further clinical use, a chart of normal growth centiles of fetal UAV in utero was then calculated based on this equation. In conclusion, we believe our data of fetal UAV assessed by 3-D US can serve as a useful reference in evaluating fetal growth and nutrition status during gestation.

Prenatal diagnosis of arthrogryposis multiplex congenita with increased nuchal translucency but without any underlying fetal neurogenic or myogenic pathology

Arthrogryposis multiplex congenita is a general term for congenital multiple joint contractures, the aetiology of which is variable. Prenatal diagnosis is usually based on the detection of diminished fetal movements and joint contractures on ultrasound. There are also reports of early diagnosis of arthrogryposis in the first and early second trimester by detection of subcutaneous oedema. We report another case of arthrogryposis multiplex congenita with increased nuchal translucency and scoliosis diagnosed by ultrasonography at 15 weeks of gestation. The pregnancy was terminated at the request of the parents. Post-mortem examination revealed that it was not associated with fetal myopathy or neuropathy. Multiple joint contractures with increased nuchal translucency without any underlying fetal neurogenic and myogenic pathology may be a distinct form of arthrogryposis multiplex congenita.

Development of the arterial pattern in the upper limb of staged human embryos: normal development and anatomic variations

A total of 112 human embryos (224 upper limbs) between stages 12 and 23 of development were examined. It was observed that formation of the arterial system in the upper limb takes place as a dual process. An initial capillary plexus appears from the dorsal aorta during stage 12 and develops at the same rate as the limb. At stage 13, the capillary plexus begins a maturation process involving the enlargement and differentiation of selected parts. This remodelling process starts in the aorta and continues in a proximal to distal sequence. By stage 15 the differentiation has reached the subclavian and axillary arteries, by stage 17 it has reached the brachial artery as far as the elbow, by stage 18 it has reached the forearm arteries except for the distal part of the radial, and finally by stage 21 the whole arterial pattern is present in its definitive morphology. This differentiation process parallels the development of the skeletal system chronologically. A number of arterial variations were observed, and classified as follows: superficial brachial (7.7%), accessory brachial (0.6%). brachioradial (14%), superficial brachioulnar (4.7%), superficial brachioulnoradial (0.7%), palmar pattern of the median (18.7%) and superficial brachiomedian (0.7%) arteries. They were observed in embryos belonging to stages 17-23 and were not related to a specific stage of development. Statistical comparison with the rates of variations reported in adults did not show significant differences. It is suggested that the variations arise through the persistence, enlargement and differentiation of parts of the initial network which would normally remain as capillaries or even regress.

Transcriptional regulation of the gene for epidermal growth factor-like peptides in sea urchin embryos

Exogastrula-inducing peptides (EGIPs), which are epidermal growth factor-related peptides of the sea urchin Anthocidaris crassispina, are substances that elicit abnormal gastrulation (exogastrulation) during embryogenesis of the sea urchin. In the present study we have examined the regulation of the expression of the EGIP precursor gene (EGIP) in sea urchin embryos. Whole mount in situ hybridization showed that EGIP is zygotically expressed afterthe onset of gastrulation in subdomains of the embryonic and larval ectoderm. The expression is confined in early gastrulae to small ectodermal regions adjoining the vegetal plate, which progressively expand to almost the entire ectoderm except the oral hood and postoral tips of the arms in later stages. In adults the expression is restricted to the ovary. Zygotic EGIP expression is sensitive to dissociation of embryonic cells, as well as to disruption of the extracellular matrix (ECM) with 5-cis-hydroxyproline, suggesting requirements for interaction with neighboring cells and/or with the ECM. The expression of reporter genes (chloramphenicol acetyl transferase and green fluorescent protein) under the regulation of the 4.6 kb upstream region of EGIP is temporally and spatially similar to that of the endogenous gene, showing that EGIP expression is regulated at the transcription level during embryogenesis by the cis-elements within the 4.6 kb upstream region.

Antepartum detection of macrosomic fetus: clinical versus sonographic, including soft-tissue measurements

OBJECTIVE

To compare clinical and sonographic estimates of birth weights with five new estimation techniques that involve measurements of soft tissue, for identifying newborns with birth weights of at least 4000 g.

METHODS

Over 1 year, each woman at or after 36 weeks' gestation and suspected of having a macrosomic fetus had clinical and sonographic estimates of fetal weight (EFW) based on femur length (FL) and head and abdominal circumference, followed by five additional ways to identify excessive growth: cheek-to-cheek diameter, thigh soft tissue, ratio of thigh soft tissue to FL, upper arm subcutaneous tissue, and EFW derived from it. Areas (+/- standard error) of receiver operating characteristic (ROC) curves were calculated and compared with the area under the nondiagnostic line. P <.05 was considered statistically significant.

RESULTS

Among 100 women recruited, 28 newborns weighed 4000 g or more. The areas under the ROC curves with clinical (0.72 +/- 0.06) and sonographic predictions using biometric characteristics (0.73 +/- 0.06) had the highest but similar accuracies (P.05). Three of the five newer methods (upper arm or thigh subcutaneous tissue and ratio of thigh subcutaneous tissue to FL) were poor diagnostic tests (range of areas under ROC 0.52 +/- 0.06 to 0.58 +/- 0.07). Estimated fetal weight based on upper arm soft tissue thickness and cheek-to-cheek diameter (areas 0.70 +/- 0.06 and 0.67 +/- 0.06, respectively) were not significantly better than clinical predictions (P.05) for detecting macrosomic fetuses. About 110 macrosomic and nonmacrosomic infants combined would be needed to have 80% power to detect a difference between ROC curves with areas of 0.58 (thigh subcutaneous tissue) and 0.72 (clinical estimate).

CONCLUSION

ROC curves indicated that measurements of soft tissue are not superior to clinical or sonographic predictions in identifying fetuses with weights of at least 4000 g.

Prenatal findings in Brachmann-de Lange syndrome

We present a case of Brachmann-de Lange syndrome, in which prenatal ultrasonographic evaluation demonstrated increased nuchal translucency, early onset of intrauterine growth retardation, and limb abnormalities in the first, second, and third trimester, respectively.

Prenatal sonographic diagnosis of Holt-Oram syndrome

Holt-Oram syndrome is an autosomal dominant disorder characterized by heart defects in combination with characteristic upper-limb abnormalities. A woman with no family history of genetic diseases underwent prenatal sonography at 25 weeks' menstrual age to screen for fetal anomalies. Sonography revealed abnormalities in the upper limbs and heart. The limb abnormalities included bilateral absence of radii and thumbs: the left hand had no carpal or metacarpal bones, and each of the 4 fingers on that hand had only 1 phalangeal bone. Cardiac malformations included an atrial septal defect and Ebstein's anomaly. Other structures were normal. Prenatal cytogenetic analysis by cordocentesis revealed a normal 46,XY karyotype. Spontaneous labor and delivery at 34 weeks' menstrual age produced a 1,960-g male infant who died of cardiac insufficiency shortly after birth. The postnatal appearance and autopsy findings confirmed the prenatal findings. In this case, Holt-Oram syndrome was readily diagnosed by prenatal sonography.

Limb development: Farewell to arms

Forelimbs and hindlimbs are, clearly, quite different, and it has long been appreciated that their differences are assigned early in development; the genetic basis of these differences has been more mysterious, however. Recent work has now shown that the homeobox gene Pitx1 imparts identity to the developing hindlimb bud.

The drug line: the clinical expression of the pigmentary Voigt-Futcher line in turn derived from the embryonic ventral axial line

BACKGROUND

Observation of patients with morbilliform eruptions reveals a distinctive demarcation line on the upper arms.

OBJECTIVE

We studied the origin of this sharp "drug line."

METHODS

We performed a literature search of all known variables.

RESULTS

The drug line represents clinical expression of the pigmentary Voigt-Futcher line.

CONCLUSION

The drug line reveals the otherwise inapparent embryologic ventral axial line, which marks the precise border between the sensory innervation of the lateral and medial upper arm. The significance of the cutaneous sensory nerves is thus apparent. The drug line is further evidence of the segmental nature of human skin, as evidenced in evolutionary and embryologic studies.

[Can 3D volumetric analysis of the fetal upper arm and thigh improve conventional 2D weight estimates?]

AIM

To determine the usefulness of three-dimensional ultrasound volumetry of fetal thigh and upper arm in predicting weight at delivery.

METHOD

Inclusion criteria to our prospective study were single-ton pregnancies with a planned or expected delivery within 96 hours of enrollment. In 74 patients (formula-finding group) standard fetal biometry, followed by measurement of thigh and upper arm volumes by three-dimensional ultrasound, was performed. Subsequently, our new 3D-formulas were tested in a prospective validation group of 52 patients.

RESULTS

Both upper arm and thigh volumes correlated well with birth weight (r2 = 0.95, respectively, p < 0.0001). The best result, however, was achieved by a combination of standard 2D-measurements with the volumetric data of upper arm and thigh (r2 = 0.98, p < 0.0001). With use of polynomial regression analysis we obtained two best-fit formulas: BIRTH WEIGHT: -263.8 +13.7269 x Arm Volume +7.16575 x Thigh Volume +148.2 x ATD. Birth weight: -1288.7 +51.9502 x Arm Volume -0.252 x Arm Volume 2 -2.1766 x Thigh Volume +0.0321 x Thigh Volume 2 +36.2509 x GA -0.7526 x GA2 +654.3 x BIP -36.6136 x BIP2 -381.8 x ATD +24.0927 x ATD2.

CONCLUSION

Three-dimensional volumetry of the fetal thigh and upper arm may improve prediction of birth weight. Further larger studies are needed to validate our results.

Lateralised behaviour in first trimester human foetuses

Behavioural lateralisation is a common feature of everyday behaviour, most familiar in the exhibition of handedness. Despite differing theories about the origins of laterality, little is known about their ontogenesis. This study observed the left and right arm movements of 72 foetuses at 10 weeks of gestational age, the first age at which lateralised behaviour may be observed. There was a highly significant preference for foetuses to move their right arm more than their left arm, 85% exhibiting more right arm than left arm movements. There was no difference in the amount of movements exhibited with the preferred arm, whether it be right or left. Laterality of behaviour at such an early gestational age (probably as early as it is possible for it to be observed) is unlikely to be under brain control but is probably of more muscular or spinal determination. The possibility that early differential motor behaviour may contribute to subsequent laterality of behaviour and asymmetrical brain growth, must be considered.

Prenatal development of arm posture

Fetal arm posture was studied longitudinally in 10 uncomplicated pregnancies using real-time ultrasound. Observation were performed at four weekly intervals from 12 to 36 weeks, and at 38 weeks. The percentage of assessments with optimal visualization of elbow, wrist and fingers was 84% at 12 weeks and more than 90% thereafter (range 92-98%). There was a clear developmental trend towards increased flexion. Flexion of the elbow occurred frequently from 12 weeks onwards with an increased incidence at 16 weeks, that in the fingers from 20 weeks onwards and from 28 weeks to term age in the wrist. All three trends were statistically significant. There was considerable intra-individual consistency in terms of the ages at which flexion increased. In fact the increase of flexion occurred one session later in only 6/30 registrations. The combined data of the elbow, wrist and fingers revealed preferential arm posture at 12 weeks with the elbow flexed and the wrist and fingers extended. From 16 to 28 weeks, the predominant posture consisted of elbow flexion, wrist extension and finger flexion and complete flexion thereafter. The development of fetal arm posture does not comply with a proximo-distal trend in that there was first an increase in flexion at the elbow, followed by the fingers and finally the wrist. The implications of our findings for understanding the prenatal development of the central nervous system and subsequent postural adjustments to extrauterine life are discussed.

Genetics of limb development and congenital hand malformations

The vertebrate limb bud develops along three different axes: proximodistal, anteroposterior, and dorsoventral. Several genetic factors responsible for control of each of the three limb axes have been identified. The genes involved interact in complex feedback loops to achieve proper arrangement and differentiation of tissues. Most of the available information on limb development and patterning has come from studies carried out in the lower vertebrates. In recent years, an increasing number of studies have been unraveling the genetic basis of human hand malformation phenotypes. At present, genes responsible for preaxial polydactyly, split hand/split foot malformation, and brachydactyly type C have been localized, and the gene responsible for synpolydactyly has been identified. In this paper, we present an overview of the genetic factors involved in limb development, followed by summarized discoveries in the genetics of human congenital hand malformations.

Predicting birth weight by fetal upper-arm volume with use of three-dimensional ultrasonography

OBJECTIVE

Our purpose was to determine the usefulness and accuracy of the three-dimensional ultrasonography assessed fetal upper-arm volume in predicting birth weight.

STUDY DESIGN

From June 1996 to October 1996, we performed a prospective study of ultrasonography on 105 pregnant women without fetal structural anomaly or aneuploidy. Both the traditional two-dimensional ultrasonographic parameters and three-dimensional ultrasonography for fetal upper arm volume were measured within 48 hours of delivery.

RESULTS

The upper arm volume correlated well with birth weight (r = 0.92, n = 105, p < 0.0001). With use of linear and polynomial regression, we obtained a best-fit new formula, Birth weight = 1088.60 + 36.024 x Upper-arm volume. The accuracy of this new formula is compared with that of two Chinese equations predicting fetal weight reported before and other formulas commonly used in the world as well. Our formula is more accurate in predicting birth weight than all the other formulas by traditional two-dimensional ultrasonography, either in error, percentage error, or absolute error. Another group by prospective validation further proved this finding.

CONCLUSION

The upper-arm volume assessed by three-dimensional ultrasonography can accurately predict birth weight, and its accuracy is superior to the previous, formulas. Our study has at least validated the application of upper-arm volume by three-dimensional ultrasonography in estimating fetal weight. Further larger series are needed to confirm our findings.

Developmental sequence of human fetal body movements in the second half of pregnancy

To describe fetal body movements precisely and to clarify their developmental sequence in the second half of pregnancy, fetal body movements were observed in 31 normal fetuses between 20 and 41 weeks of pregnancy by using multiple ultrasonic machines. All movements of the whole trunk were able to be classified into six fundamental movements: flexion, stretch, rolling, startle, stepping, and writhing. Startle was always observed as a single movement, but others were more frequently observed as a part of combination rather than as a single movements. The incidence of flexion and stretch peaked at 28-31 weeks, whereas the incidence of startle and stepping lowered at the period. The incidence of rolling and upper half trunk movements increased at 40-41 weeks. Limb movements were frequent and did not exhibit characteristic change in the incidence. In conclusion, we classified fetal body movements into several fundamental movements instead of using the expression of "general movements" by focusing principally on movements of the trunk. In particular, some of the fundamental movements seem to appear in characteristic ways as related to gestational age. In view of that fetal behaviors are closely related to the neural activity, the present findings may contribute to an understanding of the developmental process of the central nervous system.

Mutations in human TBX5 [corrected] cause limb and cardiac malformation in Holt-Oram syndrome

Holt-Oram syndrome is characterized by upper limb malformations and cardiac septation defects. Here, we demonstrate that mutations in the human TBX5 gene underlie this disorder. TBX5 was cloned from the disease locus on human chromosome 12q24.1 and identified as a member of the T-box transcription factor family. A nonsense mutation in TBX5 causes Holt-Oram syndrome in affected members of one family; a TBX5 missense mutation was identified in affected members of another. We conclude that TBX5 is critical for limb and heart development and suggest that haploinsufficiency of TBX5 causes Holt-Oram syndrome.

Congenital disorders of the hand and upper extremity

This article summarizes normal formation and growth of the upper limb as a basis for understanding malformation. Shoulder anomalies, including Sprengel's undescended scapula, clavicle pseudarthrosis, cleidocraniodystostosis, and Poland's syndrome, are presented. Classification and examples of limb malformations are discussed as well as neuromuscular disorders, such as obstetric brachial plexopathy, cerebral palsy, and arthrogryposis. The author hopes that this article provides a basic understanding of the evaluation necessary for appropriate counseling and referrals for treatment of the child with hand and upper extremity congenital deformities.

Ultrastructure of developing muscle in the upper limbs of the human embryo and fetus

BACKGROUND

The ultrastructure of the myogenesis, which proceeds along with the appearance of muscle-specific proteins and isozymes, has not been fully described in the upper limb of staged human embryos.

METHODS

Eight human embryos (Carnegie stage 14-22) and two fetuses (11 and 12 weeks of gestation) were fixed with 5% glutaraldehyde, 4% paraformaldehyde, and 0.2% picric acid in 0.1 M phosphate buffer, pH 7.2. The upper limbs were dissected out and processed for transmission electron microscopy, and sections of the biceps brachii muscle were cut and examined.

RESULTS

At stage 14, the myoblasts were loosely scattered in the ventral proximal region of the upper limb bud and had a small amount of cytoplasm with a few intracellular organelles. At stage 16, the myoblasts were spindle shaped and oriented parallel to the axis of the upper limb bud. These cells had irregularly shaped nuclei with prominent nucleoli, rough endoplasmic reticulum (ER), and mitochondria, but no myofilaments were observed. At stages 17-19, rough ER, free ribosomes, and mitochondria increased in number and thick and thin filaments with faint Z-lines appeared in the peripheral cytoplasm of the myotube. The plasma membranes of some neighboring myotubes were continuous, suggesting that these cells were in the initial stages of the fusion process. At stage 22, the striated pattern of the myofilaments became evident and tubular structures appeared around them and near the plasma membrane. In the fetus at the 11th week, the basal lamina began to surround the myotubes, and T-tubules with sarcoplasmic reticulum were observed. Dyads and triads were observed in the myotube of the 12th week fetus.

CONCLUSION

These findings suggest that rapid myogenesis occurs during the late embryonic period in human upper limbs and that the ultrastructural characteristics of mature myotubes are established during the early fetal period.

Congenital constriction band syndrome. Pathophysiology and treatment

The clinical manifestations of 88 children with congenital constriction band syndrome involvement of the hand were reviewed. Seventy-five of these children had evidence of digital or limb amputations, with 235 upper limb amputations and 138 lower limb amputations. In the hand, digital amputations were most common in the index, middle, and ring fingers, whereas in the foot, amputations of the hallux were most often noted. Band indentation was often present at multiple levels. Proximal bands may be associated with neural compression. Syndactyly was invariably associated with a proximal interdigital sinus or cleft and was frequently associated with distal amputation. Examination of a 27-week gestation stillborn specimen having manifestations of congenital constriction band syndrome demonstrated the intrauterine biologic response to band constriction. The variable clinical manifestations of congenital constriction band syndrome can best be explained as the response of the growing, embryologically defined limb to intrauterine deformation or band-induced compression and ischemia.

Ultrasonography of the normal and abnormal antenatal development of the upper limb

The degree of severity of congenital deformities of the hand, as well as any coexisting congenital anomaly should be evaluated especially if there is a possibility of therapeutic termination of pregnancy. This may be relatively easy in the case of some major malformations which affect the neurological or intellectual capacity of the child. It is however more difficult in the presence of predominantly motor anomalies, and with distally based anomalies of the upper limb which may be amenable to later reconstructive surgery.

Character phylogeny of the primate forelimb superficial venous system

The ontogeny and comparative anatomy of the forelimb superficial veins were investigated in humans, non-human primates and other mammals. Adult humans and the orangutan (Pongo) possess two autonomous forelimb veins, one on the lateral (preaxial) margin of the limb, the other on the medial (postaxial) margin. All other adult primates and mammals examined possess a lateral vein alone. In African apes (Pan and Gorilla) and in 24% of human forelimbs the lateral vein is short, being essentially confined to the antebrachial region, whereas in other mammals and in 76% of human limbs the lateral vein runs from the carpus to the clavicular region. In humans the medial vein develops before the lateral vein, whereas in the rabbit and the pig the medial vein is present in early embryos but is subsequently lost. We propose that in humans, and probably also in the orangutan, the possession of a medial vein is a neotenic retention of a primitive tetrapod condition. These animals, which retain their medial vein, are united by losing a late stage in their ontogeny. Other animals subsequently pass through a stage in which the medial vein is lost, but Pongo and Homo retain this vein to adulthood. The loss of an ontogenetic stage can arise independently, and the presence of a medial vein therefore affords only weak evidence for a close phylogenetic relationship between humans and the orangutan. The polymorphic lateral vein of humans may be a character state that is intermediate between the derived (short) lateral vein of the African apes and the primitive long lateral vein of other non-human primates and mammals.

Mode of expression of muscle-type enolase isozyme in the developing limb bud of human embryos

The appearance of beta-enolase, a glycolytic enzyme, was studied immunohistochemically using the upper limb bud of human embryos at Carnegie stages from 13 to 21. beta-Enolase-immunoreactive cells first appeared at stage 15 in the proximal portion of the upper limb bud. It was evidenced that glycogen granules first appear at the same stage. These results may suggest that changes in energy metabolism might be one of the earliest events in the differentiating steps of the skeletal muscles because this stage is earlier than the stages of cell fusion, myofilament formation and innervation of the muscle cells.

Immunohistochemical study of creatine kinase isozymes in the human upper limb bud

Creatine kinase (CK) is involved in the production of ATP and is composed of two immunologically distinct subunits, B (CK-B) and M (CK-M). In the differentiation of myoblasts, the isozyme of CK changes from CK-B to CK-M. In the present study, the expression of CK subunits was studied immunohistochemically in the upper limb bud of human embryos (Carnegie stages 13-21). It was found that CK-B and CK-M immunoreactive cells appeared at stage 15 and at stage 18, respectively.

Study of upper extremity growth and development using human embryos and computer-reconstructed models

This study investigated the apical ectodermal ridge and early vasculature of the human limb bud by use of histologic techniques and a new method of computer modeling. Fourteen human embryos were studied (more than 10,000 sections) microscopically and the embryonic limbs were reconstructed three-dimensionally by use of a serialized programming method. The apical ectodermal ridge consists of an extensive band of specialized cells, located over the rim of the limb surmounting a strip of rapidly-dividing mesenchymal cells. It is consistently supplied by a large vessel that shows extensive central branching.

Intra-uterine growth curves for midarm and thigh circumferences

Use of birth weight as a measure of intrauterine growth is hampered by several logistic problems. Both mid-arm (MAC) and thigh circumferences (TC) have been proved to be efficient alternative measurements. In this study MAC and TC were recorded on 2925 consecutive live births to derive intrauterine growth curves and provide normative data for an indigenous population.