Ontogenetic and anatomic variation in mineralization of the wing skeleton of the Mexican free-tailed bat, Tadarida brasiliensis

We examined patterns of variation in the mineral content of the wing skeleton of the Mexican free-tailed bat, Tadarida brasiliensis. We ashed humeri, radii, metacarpals II-V, and phalanges of digit III, and quantified mineralization differences among elements at specific ages, and ontogenetically for each element. The most mineralized elements are the humerus and the radius, followed by the metacarpals, of which the third and fifth are the most mineralized. The proximal and middle phalanges of the third digit exhibit the lowest mineral content, and the distal phalanges have no mineral content according to our ashing protocol. Histological examination shows a thin (< 10 μm) shell of unmineralized osteoid surrounding a cartilaginous core in distal phalanges. Mineral content of each bone increases linearly with age during post-natal development, but there are differences in the rate and extent of this increase among the different elements.
The mineralizaton differences we observed parallel substantially different bone loading patterns found in different parts of the wing in other studies. The humerus and radius are subjected to large torsional loads during flight, while the metacarpals and phalanges experience dorsoventral bending. The high mineral content of the humerus and radius and the low mineral content of the metacarpals and phalanges may resist torsion proximally and promote bending distally. Furthermore, the decrease in mineral content along the wing's proximodistal axis decreases bone mass disproportionately at the wing tips, where the energetic cost of accelerating and decelerating limb mass is greatest.     

Comparative and functional morphology of hominoid fingers.

Comparisons of hominoid metacarpals and phalanges reveal differences, many of which are closely linked to locomotor hand postures. The African apes display features of the metacarpals and phalanges which distinguish them from the other Hominoidea. These features are most evident in digits III and IV. The orangutan hand is demonstrably less well adapted to knuckle-walking and is distinctive in its adaptation to power and hook grasping of vertical and horizontal supports, respectively. Orangutan fingers possess a "double-locking" mechanism (Napier, '60), and a slight ulnad shift in the axis of the hand which results in lengthened phalanges of ray IV. Hylobatid apes are more like orangutans in their finger morphology than any of the other Hominoidea, but exhibit unique features of their own. These include elongate phalanges of fingers II-V. Human metacarpals II-V form two sets composed of II-III, and IV-V. The heads of both metacarpals II and III are characterized by axial torsion. This reflects the enhanced manipulatory role of the third finger in humans. Human distal phalanges are unique in the development of pronounced apical tufts. Multivariate analysis of metacarpal III and proximal III yields variables that array the extant apes along an arboreal-terrestrial axis, from hylobatid apes to male gorillas. The positions of taxa on this discriminant concur with observations on the locomotion of free-ranging apes.     

Metacarpophalangeal length changes in humans during adulthood: a longitudinal study.

Total lengths of the 19 diaphyseal hand bones were measured from standardized radiographs of healthy American whites as young adults (ca. 21 years) and again at ca. 55 years of age. The four hand-bone rows exhibit distinctive length changes: Distal and middle phalanges continue to increase significantly in length, proximal phalanges constitute a transition zone of little change, and metacarpals uniformly decrease in length. Clear-cut sex differences are noteworthy: Males change more (lose more in some bone rows, gain more in others) than females. Progressive elongation was greatest in the distal phalanges where apposition around the distal aspect ("tufting") is not constrained by a joint or epiphysis. Loss of bone length in the metacarpals by subchondral resorption is consistent with documented reductions in activity levels and grip strength with age, as well as diminished joint spaces which alter loading of the joints.     

Digit effects produced by prenatal exposure to antiepileptic drugs

The hypothesis tested was that digit anomalies among individuals exposed in utero to antiepileptic drugs (AED) are best identified by a systematic search, including radiographs and dermatoglyphics, rather than relying only on visual inspection. A systematic search was made for five types of digit abnormalities in 46 AED-exposed individuals ages 5-29 years in comparison with controls: visible anomalies, size of fingernails, dermal ridge patterns, length of metacarpals and phalanges, and qualitative changes in the distal phalanges. Among the AED-exposed, nail size was not decreased. However, there was a 10.8% frequency of digit anomalies, a 12% frequency of three or more arch patterns, and significant shortening and qualitative changes in the distal phalanges, all of which are consistent with the fetal effects of AED. Among the 42 individuals who underwent all evaluations, 14.3% had two or more of these abnormalities, most of which would not be identified by clinical inspection. This frequency is much higher in these AED-exposed individuals than in the general population. Radiographs in 13 individuals over a period of several years showed that the changes in the phalanges and metacarpals persisted.     

Tubular hand bone growth during the latter half of the prenatal period: an allometric analysis

The growth of the 19 tubular hand bones from fetal months 5 to 9 was studied by the allometric method. The hand bones were carefully dissected under a low power stereoscopic microscope. The length and breadth of all bones was found to be monophasic in relation to crown-rump length. In general, maximum bone and ossified shaft lengths in the same row group demonstrate similar allometric coefficients. The specific growth rate of ossified shaft length for all fetal hand bones is greater than the growth rate of maximum length. The highest allometric coefficients for both maximum length and ossified shaft length were obtained from the middle phalanges. The shape of the metacarpals and distal phalanges becomes thinner, while the other bones become thicker or maintain their length-breadth ratio. The relative growth pattern of the first proximal phalanx differed from the middle phalangeal group of the other digits. This suggests that current nomenclatures for the three bones of the pollex is appropriate.     

A resampling approach and implications for estimating the phalangeal index from unassociated hand bones in fossil primates

Primate fossil assemblages often have metacarpals and phalanges from which functional/behavioral interpretations may be inferred. For example, intrinsic hand proportions can indicate hand function and substrate use. But, estimates of intrinsic hand proportions from unassociated hand elements can be imperfect due to digit misattribution. Although isolated metacarpals can be identified to a specific digit, phalanges are difficult to assign to a specific ray. We used a resampling approach to evaluate how estimates of intrinsic hand proportions are affected by such uncertainty. First, the phalangeal index—intermediate phalanx length plus proximal phalanx length divided by metacarpal length—for the third digit was calculated for associated specimens of terrestrial, semiterrestrial, and arboreal taxa. We then used resampling procedures to generate distributions of “composite digits” based on resampled ratios in which phalanges from the second, fourth, and fifth rays, and from different individuals, were chosen randomly. Results confirm that the phalangeal index for associated third digits significantly discriminates groups. We also found that resampled ratios had significantly lower means, indicating that using composite digits is prone to systematic underestimation. Resampled ratios also generated distributions with greater variance around the means that obscured distinctions between groups, although significant differences between the most arboreal and terrestrial taxa are maintained. We conclude that using unassociated phalanges to calculate a phalangeal index is prone to sampling bias. Nevertheless, a resampling approach has the potential to inform estimates of hand proportions for fossil taxa, provided that the comparative sample is constrained to mimic the fossil composition. Am J Phys Anthropol 151:280–289, 2013. © 2013 Wiley Periodicals, Inc.     

Notches in the non-epiphyseal ends of the metacarpals and phalanges in children of four South African populations

The incidence of notches in the non-epiphyseal ends of the shafts of the metacarpals and phalanges was determined from radiographs of the left hand of 1,303 Pretoria school-children aged 6 to 11 years. The group included White, Negro, Coloured and Indian children. The notches represent vestiges of supernumerary epiphyses or pseudo-epiphyses. Notching of one or more of the metacarpals or phalanges was found in 88.9% of White children, 77.1% of Negro children, 84.3% of Coloured children and 78.8% of Indian children. Notches were most common in metacarpal I followed in declining order of frequency by metacarpal II, metacarpal V, middle phalanx V and proximal phalanx I. Notches were rare in other sites. The mean number of notches per subject was significantly higher in males than in females in all four population groups. However, the sex differences appear to be due mainly to earlier obliteration of notches in females. The findings in White children suggest that there is no significant relationship between metacarpal and phalangeal notching and skeletal maturation rate. Notches are significantly more common in Pretoria Whites than in relatively poorly nourished Pretoria Negro children. It is concluded that the occurrence of notches is a normal phenomenon accompanying the ossification of the hand skeleton and that notching is related neither to retardation in skeletal development nor to undernutrition.     

Allometric patterning in the limb skeleton of bats: Implications for the mechanics and energetics of powered flight

Allometric analysis was employed to compare linear dimensions of forelimb and hindlimb bones (humeri, radii, third and fifth metacarpals, third and fifth manual phalanges, femora, and tibiae) of 227 species of bats and 105 species of nonvolant mammals of varying degrees of phylogenetic affinity to bats. After accounting for body size, all forelimb bones are longer in bats than in nonvolant species, with the exception of humeri and radii of a few highly arboreal primates. Hindlimb bones are generally, but not uniformly, shorter in bats than in other mammals. For the humerus, radius, and metacarpals, midshaft diameters are greater in bats than in their comparably sized relatives. Proximal phalangeal midshaft diameters are statistically indistinguishable from those of other mammals, and distal phalanges show significantly reduced outer diameters. The pattern of relative reduction in wing bone diameters along the wing's proximodistal axis parallels the reduction in bone mineralization along the same axis, and a similar pattern of change in cortical thickness from the smallest wall thicknesses among mammals in the humerus and radius to the greatest wall thicknesses among mammals in the phalanges. The combination of altered cross-sectional geometry and mineralization appears significantly to reduce the mass moment of inertia of the bat wing relative to a theoretical condition in which elongated bones preserve primitive mammalian mineralization levels and patterns of scaling of long bone diameters. This intercorrelated suite of skeletal specializations may significantly reduce the inertial power of flight, contributing significant energetic savings to the total energy budgets of the only flying mammals. J. Morphol. 234: 277–294, 1997. © 1997 Wiley-Liss, Inc.     

Rigid internal fixation in the hand: 104 cases

One-hundred and four patients with fractures of the metacarpals and phalanges have been treated with rigid internal fixation over a 6-year period. Patients with both open and closed injuries had their fractures fixed by tension band wires, interosseous compression screws (lag screws), or plates and screws. The concepts of primary bone healing and its variations, methods of fixation, and the importance of interfragmentary compression are defined and stressed. Illustrative cases of each technique are described and the applicable principles are enunciated.     

Applications of radiodermatography to human and primate studies

Using 325-mesh tantalum powder as a contrast medium, it is possible to take high-resolution “radiodermatographs” of man and infra-human primates that combine the advantages of postero-anterior hand radiographs and conventional paper palm-and-finger prints. The radiodermatographs are particularly useful in relating creases, triradii and fingertip ridge patterns to differences in the proportions of the carpals, metacarpals and phalanges.     

A variant of Cenani-Lenz type syndactyly

Cenani-Lenz syndrome is a form of complete syndactyly resembling the spoon hand in Apert syndrome. It is often associated with disorganization of phalanges, the fusion of metacarpals and mesomelic shortness of the arm. We describe an additional case of Cenani-Lenz type of syndactylism in a 16 month-old girl who also has rib and vertebral abnormalities and mixed type hearing loss, that have not been seen before in a single patient.     

Ectrodactyly/split hand feet malformation

Split-hand/split-foot malformation is a rare limb malformation with median clefts of the hands and feet and aplasia/hypoplasia of the phalanges, metacarpals and metatarsals. When present as an isolated anomaly, it is usually inherited as an autosomal dominant form. We report a case of autosomal recessive inheritance and discuss the antenatal diagnosis, genetic counseling and treatment for the malformation.     

Some aspects of the analysis of hand-wrist bone-age readings

Principal components analysis was applied to the individual center bone-age readings from the study outlined by Sproul and Peritz ('71) in the preceding paper. The first two components are amenable to a simple interpretation. The first one is a general skeletal maturity factor, which can be expressed as a weighted mean bone-age, with slightly higher weights attached to the metacarpals and phalanges II to V than to the other bone centers. The second component is a measure of the contrast between hand-bone and finger-bone ages, with generally high positive weights for the bone-ages of radius and carpals, low weights for metacarpals and negative weights for phalanges. The weights for the first component vary little between races and sexes or with children's height. The weights for the second component are less homogeneous. The first component accounts for some two thirds of the variability; the second component accounts for roughly nine percent of it. Mean values for the first two components vary considerably with the children's height. Various other results relating the first two components to height and parents' height are presented. An analysis of the correlation matrices of individual center bone ages revealed particularly high correlations (0.8 to 0.9) within rows, with the exception of thumb bone centers.     

Shankless, a new mutation on chromosome 2 in the chicken

A mutant condition characterized by absence of shanks is invariably present in chickens that are homokaryotypic for an X-ray-induced pericentric inversion to chromosome 2. The mutation was studied in 260 embryos at 19 days of incubation. Embryos produced from matings of parents with and without the inversion were karyotyped and their skeletons observed and measured. The mutant phenotype, which was seen in all birds homokaryotypic for the inversion, is characterized by malformed and reduced metacarpals, absence of tarsometatarsal shanks, increased tibia length, extra bones in digits two, three, and four, and fusion of proximal phalanges. Heterokaryotypic and homokaryotypic normal embryos had normal phenotypes, but the length of metacarpals was slightly reduced in heterokaryotypes. The primary effect of the mutation is to cause misplacement, malformation, and underdevelopment of metatarsals II, III, and IV. The recessive mutation, located in the proximal region of chromosome 2, has been designated shankless (shl).     

Male advancement in prenatal hand development

Male advancement in the developing hand was evidenced by 66 grossly and microscopically normal embryos in the 15–75 mm crown-rump range. Male advancement was particularly pronounced in the younger (15–30 mm) embryos, both in the proximal hand region including the round bones of the wrist and in the distal hand region, comprising the metacarpals and phalanges. Thirty-four additional embryos, abnormal in implantation or development or representing spontaneous abortion similarly evidenced male advancement in the early hand skeleton.     

Metacarpophalangeal pattern profiles in Venezuelan and northern Caucasoid samples compared

Comparison of hand long-bone lengths and variances in published measurements of North American Caucasoid, Venezuelan, and English individuals, and of their metacarpophalangeal pattern profiles (MPP), revealed systematic differences between samples from infancy through adulthood. The variances of Venezuelan males tend to be larger than those of Americans, especially under 9 years of age. The same trend was observed for females, but to a lesser degree. The English sample showed variance similar to that of Venezuelans and Americans. Below 7 years of age, bones of Venezuelans were longer than those of Americans, except the distal phalanges, which always were longer in the latter, as were all bones after age 17. The index finger's middle and distal phalanges of Americans were relatively longer than the other bones at all ages. Females also showed this general trend, though not as clearly. Venezuelan adults had longer first and second metacarpals and proximal phalanges than the English adult homologs. American adults had all bones longer than those of English adults. The English adults showed a "typical" MPP, characterized by shorter proximal phalanges, both when compared with Venezuelan and with American adults. Genetic rather than environmental causes are likely as an explanation for these differences. This warned us against the indiscriminate use of any "standard" sample from a different population to establish objective profile patterns and sizes in abnormal cases, as illustrated with one example.     

短指/趾的分子遗传学研究进展

短指/趾(Brachydactyly, BD)是指(趾)骨和/或掌(跖)骨短小、缺失或融合导致的手/足先天畸形, 是一组以骨发育障碍为特征的肢体畸形疾病。BD可单独出现, 也可作为综合征的一种体征, 还可伴随其他的手/足畸形如并指/趾、多指/趾、短缺畸形和指/趾骨关节融合出现。绝大多数单纯型BD呈常染色体显性遗传, 存在表现度不同和外显不全。大多数单纯型BD和一些综合征型BD的致病基因缺陷已经被鉴定。BMP (Bone morphogenetic protein)通路参与正常指/趾发育, 且已知的BD致病基因直接或间接参与该通路。文章综述了BD分子遗传学研究方面的新进展, 将有助于BD致病机制的研究和基因诊疗的开展。     

Stereoradiogrammetric technique for estimating alignment of the joints in the hand and wrist

A method and apparatus for quantitative measurement of the alignment and motion of the joints of the hand in three dimensions has been developed using stereoradiogrammetric principles. Alignment in planes of flexion-extension and radial-ulnar deviation can be determined to within 2.5°; rotation about the long axis of the metacarpals or phalanges is more difficult to determine, and can be measured to within 7°. Stereo views subtending angles in the range of 40° were found to optimize the total system accuracy.     

Involvement of Wnt-5a in chondrogenic pattern formation in the chick limb bud

Members of the Wnt family are known to play diverse roles in the organogenesis of vertebrates. The full-coding sequences of chicken Wnt-5a were identified and the role it plays in limb development was examined by comparing its expression pattern with that of two other Wnt members, Wnt-4 and Wnt-11, and by misexpressing it with a retrovirus vector in the limb bud. Wnt-5a expression is detected in the limb-forming region at stage 14, and in the apical ectodermal ridge and distal mesenchyme of the limb bud. The signal was graded along the proximal-distal axis at stages 20-28 and also along the anterior-posterior axis during early stages. It disappeared in the cartilage-forming region after stage 26, and was restricted to the region surrounding the phalanges at stage 34. Wnt-4 and Wnt-11, other members of the Wnt-5a-subclass, were expressed with a distinct spatiotemporal pattern during the later phase. Wnt-4 was expressed in the articular structure and Wnt-11 was expressed in the dorsal and ventral mesenchyme adjacent to the ectoderm. Wnt-5a expression was partially reduced after apical ectodermal ridge removal, whereas Wnt-11 expression was down-regulated by dorsal ectoderm removal. Therefore, expression of these Wnt was differentially regulated by the ectodermal signal. Misexpression of Wnt-5a in the limb bud with the retrovirus resulted in truncation of long bones predominantly in the zeugopod because of retarded chondrogenic differentiation. Distal elements, such as the phalanges and metacarpals, were not significantly reduced in size. These results suggest that Wnt-5a is involved in pattern formation along the proximal-distal axis by regulation of chondrogenic differentiation.     

Pentadactyl pattern of the avian wing autopodium and pyramid reduction hypothesis

We report herein that a pentadactyl developmental pattern is evident in early wing morphogenesis of Gallus (chicken) and Struthio (ostrich). Five avascular zones (spatially predestined locations of contiguous metacarpal and phalangeal aggregation) and four interdigital vascular spaces are established by the regression patterns of autopodial vasculature. Transient vestiges of the first and fifth metacarpals are confirmed histologically and histochemically. They lie within the preaxial-most and postaxial-most avascular zones, respectively. These observations reveal conservative patterning of the avian hand and corroborate a II-III-IV metacarpal interpretation, argue for II-III-IV identity of ossified digits in birds, and favour a simple reduction rather than a homeotic shift in terms of the phenotype expressed by Hox genes in the phylogeny of the avian manus. We suggest that gradual, bilateral reduction of phalanges and metacarpals, via apoptosis mediated by BMP, occurred during the evolution of birds (Pyramid Reduction Hypothesis). This is congruent with the establishment of a central wing axis that became co-opted for coordinated movements. On the basis of evidence presented here, the direct avian ancestor is predicted to have been five-fingered with dominant digits (+ metacarpals) as follow: II, III, IV.