Intrauterine growth retardation, mild frontonasal dysplasia, phocomelic upper limbs with absent thumbs and a variety of internal malformations including choanal atresia, congenital heart defects, polysplenia, absent gall bladder as well as genitourinary anomalies. A possibly "new" MCA syndrome?

Report on a female infant who showed intrauterine growth retardation; dysmorphic face with relative macrocephaly, mild frontonasal dysplasia, and small dysmorphic ears; phocomelic upper limbs with absent thumbs and radiologically poor differentiation of the long tubular bones but normal lower limbs. Autopsy revealed multiple internal abnormalities including choanal atresia, complex heart malformation, bilobed lung on the right, polysplenia, absent gall bladder as well as genitourinary anomalies. This condition represents a possibly "new" MCA syndrome with poor prognosis and yet unknown etiology.     

Homozygous Inactivating Mutations in the NKX3-2 Gene Result in Spondylo-Megaepiphyseal-Metaphyseal Dysplasia

Spondylo-megaepiphyseal-metaphyseal dysplasia (SMMD) is a rare skeletal dysplasia with only a few cases reported in the literature. Affected individuals have a disproportionate short stature with a short and stiff neck and trunk. The limbs appear relatively long and may show flexion contractures of the distal joints. The most remarkable radiographic features are the delayed and impaired ossification of the vertebral bodies as well as the presence of large epiphyseal ossification centers and wide growth plates in the long tubular bones. Numerous pseudoepiphyses of the short tubular bones in hands and feet are another remarkable feature of the disorder. Genome wide homozygosity mapping followed by a candidate gene approach resulted in the elucidation of the genetic cause in three new consanguineous families with SMMD. Each proband was homozygous for a different inactivating mutation in NKX3-2, a homeobox-containing gene located on chromosome 4p15.33. Striking similarities were found when comparing the vertebral ossification defects in SMMD patients with those observed in the Nkx3-2 null mice. Distinguishing features were the asplenia found in the mutant mice and the radiographic abnormalities in the limbs only observed in SMMD patients. The absence of the latter anomalies in the murine model may be due to the perinatal death of the affected animals. This study illustrates that NKX3-2 plays an important role in endochondral ossification of both the axial and appendicular skeleton in humans. In addition, it defines SMMD as yet another skeletal dysplasia with autosomal-recessive inheritance and a distinct phenotype.     

Comparative histopathology of the growth cartilage in short-rib polydactyly syndromes type I and type III and in chondroectodermal dysplasia

The histopathology of growth cartilage of long bones was studied in two cases of chondroectodermal dysplasia (Ellis-Van Creveld syndrome), a case of short-rib polydactyly (SRP) type I (Saldino-Noonan syndrome), three cases of short-rib polydactyly (SRP) type III (Verma-Naumoff syndrome), and a case with polydactyly without other skeletal abnormalities but with visceral malformations. The lesions were qualitatively similar in chondroectodermal dysplasia and SRP I: regular concave ossification line, short, slightly irregular columns, regularly dispersed hypertrophic chondrocytes. In SRP III, the ossification line was irregular and the hypertrophic cells had a discontinuous distribution in clusters. No amylase resistant PAS intracytoplasmic inclusions were found. Short, slightly or markedly irregular primary trabeculae, some of them with wide cartilaginous cores, tongue prolongations and islands of cartilage situated along the periost were found in chondroectodermal dysplasia, SRP I and III. The case of polydactyly without other skeletal abnormalities had a normal morphology of the growth plate. These data suggest that there is a relationship between chondroectodermal dysplasia and SPR type I, and that SRP type III is distinct from SRP type I.     

Abnormalities in cartilage and bone development in the Apert syndrome FGFR2(+/S252W) mouse

Apert syndrome is an autosomal dominant disorder characterized by malformations of the skull, limbs and viscera. Two-thirds of affected individuals have a S252W mutation in fibroblast growth factor receptor 2 (FGFR2). To study the pathogenesis of this condition, we generated a knock-in mouse model with this mutation. The Fgfr2(+/S252W) mutant mice have abnormalities of the skeleton, as well as of other organs including the brain, thymus, lungs, heart and intestines. In the mutant neurocranium, we found a midline sutural defect and craniosynostosis with abnormal osteoblastic proliferation and differentiation. We noted ectopic cartilage at the midline sagittal suture, and cartilage abnormalities in the basicranium, nasal turbinates and trachea. In addition, from the mutant long bones, in vitro cell cultures grown in osteogenic medium revealed chondrocytes, which were absent in the controls. Our results suggest that altered cartilage and bone development play a significant role in the pathogenesis of the Apert syndrome phenotype.     

Deletions in the COL10A1 gene are not associated with skeletal changes in dogs

Type 10 collagen alpha 1 (COL10A1) is a short-chain collagen of cartilage synthesized by chondrocytes during the growth of long bones. COL10A1 mutations, which frequently result in COL10A1 haploinsufficiency, have been identified in patients with Schmid metaphyseal chondrodysplasia (SMCD), a cartilage disorder characterized by short-limbed short stature and bowed legs. Similarities between SMCD and short stature in various dog breeds suggested COL10A1 as a candidate for canine skeletal dysplasia. We report the sequencing of the exons and promoter region of the COL10A1 gene in dog breeds fixed for a specific type of skeletal dysplasia known as chondrodysplasia, breeds that segregate the skeletal dysplasia phenotype, and control dogs of normal stature. Thirteen single nucleotide polymorphisms (SNPs), one insertion, and two deletions, one of which introduces a premature stop codon and likely results in nonsense-mediated decay and the degradation of the mutant allele product, were identified in the coding region. There appear to be no causal relationships between the polymorphisms identified in this study and short stature in dogs. Although COL10A1 haploinsufficiency is an important cause of SMCD in humans, it does not seem to be responsible for the skeletal dysplasia phenotype in these dog breeds. In addition, homozygosity for the nonsense allele does not result in the observed canine skeletal dysplasia phenotype. Electronic Supplementary Material Electronic Supplementary material is available for this article at and accessible for authorised users.     

Polyostotic fibrous dysplasia in a cynomolgus Macaque (Macaca fascicularis)

A 2.3-y-old female cynomolgus macaque (Macaca fascicularis) presented with a broken right tibia and fibula. Radiographs showed multiple cyst-like defects in all long bones. We suspected that both fractures were pathologic because they occurred through these defects. Ultrasonography, MRI, and dual X-ray absorptiometry revealed that the defects were filled with soft tissue. Grossly, the bones were abnormal in shape, and a gelatinous material filled the defects and the surrounding marrow cavity. Histologically, the gelatinous material was composed of fibrin and cartilage; few normal bone cells were seen. Genetic testing revealed extra material on the short arm of chromosome 8 in all tissues examined, but no copy number alterations of likely clinical significance were observed, and no abnormalities were found that were unique to the lesions. In light of the clinical signs and radiographic and pathologic findings, polyostotic fibrous dysplasia was diagnosed. This report represents the first documented case of fibrous dysplasia in a cynomolgus macaque.     

Growth and differentiation of fetal rat limb buds transplanted in athymic (nude) mice

Limb buds of day 14 rat fetuses were cut into pieces and transplanted into the subcutaneous tissue of athymic (nude) mice. In day 14 fetal limbs, mesenchymal cells have begun to condense to form cartilaginous anlage, but no cartilage has been formed. Within 7 days after grafting, masses of hyaline cartilage developed. Numerous osteoblasts appeared, and new bone formation began by 14 days. By 20 days, osteoclasts appeared, and the formation of bone trabeculae and marrow cavities progressed. The cytological characteristics of chondrocytes, osteoblasts and osteoclasts were essentially the same as those seen in vivo. Many grafts developed into long bones, having the diaphysis and epiphysis. The mode of chondrogenesis and osteogenesis in the grafts was histologically similar to the corresponding process in vivo, although the differentiation was slower in the grafted limbs. Since the grafted limb buds showed remarkable growth and tissue differentiation for at least several weeks, this heterotransplantation system would be of potential use for the study of bone formation and resorption as well as for developmental toxicological studies.     

GDF5 coordinates bone and joint formation during digit development

A functional skeletal system requires the coordinated development of many different tissue types, including cartilage, bones, joints, and tendons. Members of the Bone morphogenetic protein (BMP) family of secreted signaling molecules have been implicated as endogenous regulators of skeletal development. This is based on their expression during bone and joint formation, their ability to induce ectopic bone and cartilage, and the skeletal abnormalities present in animals with mutations in BMP family members. One member of this family, Growth/differentiation factor 5 (GDF5), is encoded by the mouse brachypodism locus. Mice with mutations in this gene show reductions in the length of bones in the limbs, altered formation of bones and joints in the sternum, and a reduction in the number of bones in the digits. The expression pattern of Gdf5 during normal development and the phenotypes seen in mice with single or double mutations in Gdf5 and Bmp5 suggested that Gdf5 has multiple functions in skeletogenesis, including roles in joint and cartilage development. To further understand the function of GDF5 in skeletal development, we assayed the response of developing chick and mouse limbs to recombinant GDF5 protein. The results from these assays, coupled with an analysis of the development of brachypodism digits, indicate that GDF5 is necessary and sufficient for both cartilage development and the restriction of joint formation to the appropriate location. Thus, GDF5 function in the digits demonstrates a link between cartilage development and joint development and is an important determinant of the pattern of bones and articulations in the digits.     

Nerve growth factor in skeletal tissues of the embryonic chick

Summary This study demonstrates, via immunohistochemistry and bioassay, the presence of NGF in embryonic bone and cartilage of the chick. Embryos were killed on days 6–9 of incubation at 12 h intervals, and on days 10–18 at 24 h intervals. Paraffin-embedded sections of hind limbs or buds were immunostained with a polyclonal antibody against NGF and the biotin-avidin-horseradish peroxidase technique. Immunostaining was positive in both bone and cartilage, with cartilage staining more intensely. For bioassay, bones from the hind limbs of 9- and 12-day embryos were fast-frozen, lyophilized, and homogenized with Medium 199 (M199). Dorsal root ganglia from 8-day embryos were cultured for 24–36 h with rooster plasma, M199, and varying concentrations of bone homogenate. Significant neurite outgrowth was seen, with the greatest response elicited by 12-day bone homogenate. Addition of anti-NGF to the cultures abolished neurite outgrowth. The results indicate that NGF is present in cartilage and bone of the chick embryo; it may determine the density of sympathetic innervation to the developing skeletal tissues.     

A microanatomical and histological study of the fin long bones of the Devonian sarcopterygian Eusthenopteron foordi

Meunier F.J. and Laurin M. 2012. A microanatomical and histological study of the fin long bones of the Devonian sarcopterygian Eusthenopteron foordi. —Acta Zoologica (Stockholm) 93 : 88–97. A paleohistological study of the endoskeletal bones of the dorsal and pelvic fins shows that Eusthenopteron foordi had true long bones that grew in length and thickness through endochondral and periosteal ossification, respectively. Endochondral ossification required cartilaginous epiphyses with a growth plate system whose presence is confirmed by both calcified cartilage and thin endochondral bony trabeculae that overlaid the erosive bays located in hypertrophic calcified cartilage. Articulations between axial mesomeres in paired fins were diarthroses. This microanatomical organization, i.e. longitudinal growth of diaphysis and articulations between epiphyses, can be considered an exaptation for terrestrial locomotion as it can produce skeletal elements able to support strong mechanical stress.     

Further studies on the effect of tetracycline on the developing skeleton of the chick embryo

At intervals from 2 to 13 days of incubation, 2.5 mg of tetracycline hydrochloride was injected into the yolk sac of chick embryos. The femurs and mandibles were examined histologically at intervals between 10 and 17 days of embryonic age. The abnormalities which result include inhibition of mineralization of the developing osteoid trabeculae, retardation of erosion of the long bone cartilage model, and abnormal calcification of the cartilage matrix in the long bones. The major effects on cartilage maturation appear to occur after cellular hypertrophy has taken place and thus are found only in cartilage models which are being replaced by bone. While tetracycline does cause some retardation in the rate of osteoid deposition, the drug appears to affect intramembraneous bone formation in the mandible and femur primarily by retarding or temporarily inhibiting the rate of mineralization of the osteoid matrix. The results of this study indicate that the effects produced by tetracycline on developing bones are dependent upon the concentration of the drug and not upon the time of administration.     

The role of hypertrophic cartilage in endochondral ossification.

Normal stages of histogenesis of long bones show that the hypertrophy of cartilage cells is the pre-requisite for the perichondrium to take up osteoblastic activity, (Fell 1925, Lutfi 1971). Cooper (1965) found the cartilage cells from epihysis of the long bones of chick failed to induce chondrogenesis in somites in mice and chick whereas flat cells and early Peripheral cells could do same. Fell and Landauer (1935) noticed that in avian phocomelia the hypertrophied cartilage cells fail to hypertrophy leading subsequently to deformities of long bones. Presently an attempt is made to analyse this process further by culture experiments. It is found that complete tibial rudiment or part of it grows normally in vitro with good differentiation of various zones and the development of osteoid tissue. However it is noticed that when cartilage and the associated perichondrial tissues are grown separately, there is no patterned growth of cartilage and the absence of development of osteoid tissue in either types of cultures. The role of perichondrium and cartilage is discussed in the light of experimental findings.     

Senile features in the skeleton of an aged Japanese monkey

The senile features in the skeleton of a male Japanese monkey, who is presumed to be about 40 years old, were examined in comparison with younger individuals. As for the skull, every part is constructed solidly, and the sutures around the temporal and parietal bones are for the most part closed. In the dentition many of the front teeth are destroyed or lost, and the cheek teeth are severely worn. In the vertebrae, the annular epiphyseal discs unite completely with the body at its anterior and posterior surfaces, and the porosity and deformation of the bodies are remarkable. The hip bones, in the pelvis, unite with each other by solid ossification of the pubic symphysis. The long bones of the anterior and posterior limbs are marked by their general thickness, the rugged increase of bone around the joints, especially in the arms, and the complete union of each epiphysis with the shaft through the ossification of the epiphyseal cartilage. These senile features furnish a clue as to the establishment of a criterion for age estimation in Japanese monkeys.This observation was briefly reported inMonkey Vol. 13, No. 1, 1969, and Fig. 9 was used there.     

A case with spondylo-metaphyseal dysplasia type A4

We present a case with spondylo-metaphyseal dysplasia type A4 characterized by ovoid vertebral bodies with anterior tongue-like deformities, widened irregular and sclerotic metaphyseal changes, short iliac wings, slightly short long bones and short tubular bones of the hands with irregular metaphyses. She also had bipartite trochlea and irregular patellar margins, which have not been described in spondylo-metaphyseal dysplasia types to date.     

河南灵井许昌人遗址动物骨骼表面人工改造痕迹

河南灵井许昌人遗址发掘出土了距今约10—8万年前的古人类头骨化石, 与头骨化石同层发现的还有大量哺乳动物化石及石制品等文化遗物。本文是对该遗址2005—2006年出土动物化石骨骼表面人工改造痕迹的观察分析结果。灵井遗址中13%的动物骨骼表面有人工切割痕的产生, 其中切割痕位于长骨骨干部位的约占此类标本总数的98.45%; 同时,在具切割痕的长骨类化石材料中,属于食草动物上部和中部肢骨的分别为34%和41%, 属于下部肢骨的则仅为25%。此外, 灵井动物群中具敲击痕、火烧痕迹、人工使用痕迹的骨骼标本分别占全部观察例数的4.2%、1%、1.32%。总之, 通过对动物骨骼表面保留的上述人工改造痕迹的观察与统计分析, 并与埋藏学实验及其他考古遗址相关属性的对比, 表明古人类是这一遗址中大量脊椎动物肉食资源的初级获取者和利用者, 他们是导致这一动物群聚集形成的主要埋藏学因素。同时, 许昌人遗址中大量破碎动物骨骼的出现可能也与古人类敲骨取髓的取食行为有着非常紧密的联系。     

Limb length and locomotor biomechanics in the genus Homo: an experimental study

The striking variation in limb proportions within the genus Homo during the Pleistocene has important implications for understanding biomechanics in the later evolution of human bipedalism, because longer limbs and limb segments may increase bending moments about bones and joints. This research tested the hypothesis that long lower limbs and tibiae bring about increases in A-P bending forces on the lower limb during the stance phase of human walking. High-speed 3-D video data, force plates, and motion analysis software were used to analyze the walking gait of 27 modern human subjects. Limb length, as well as absolute and relative tibia length, were tested for associations with a number of kinetic and kinematic variables. Results show that individuals with longer limbs do incur greater bending moments along the lower limb during the first half of stance phase. During the second half of stance, individuals moderate bending moments through a complex of compensatory mechanisms, including keeping the knee in a more extended position. Neither absolute nor relative tibia length had any effect on the kinetic or kinematic variables tested. If these patterns apply to fossil Homo, groups with relatively long limbs (e.g. H. ergaster or early H. sapiens) may have experienced elevated bending forces along the lower limb during walking compared to those with relatively shorter limbs (e.g. the Neandertals). These increased forces could have led to greater reinforcement of joints and diaphyses. These results must be considered when formulating explanations for variation in limb morphology among Pleistocene hominins.     

Nucleotide-sugar transporter SLC35D1 is critical to chondroitin sulfate synthesis in cartilage and skeletal development in mouse and human

Proteoglycans are a family of extracellular macromolecules comprised of glycosaminoglycan chains of a repeated disaccharide linked to a central core protein. Proteoglycans have critical roles in chondrogenesis and skeletal development. The glycosaminoglycan chains found in cartilage proteoglycans are primarily composed of chondroitin sulfate. The integrity of chondroitin sulfate chains is important to cartilage proteoglycan function; however, chondroitin sulfate metabolism in mammals remains poorly understood. The solute carrier-35 D1 (SLC35D1) gene (SLC35D1) encodes an endoplasmic reticulum nucleotide-sugar transporter (NST) that might transport substrates needed for chondroitin sulfate biosynthesis. Here we created Slc35d1-deficient mice that develop a lethal form of skeletal dysplasia with severe shortening of limbs and facial structures. Epiphyseal cartilage in homozygous mutant mice showed a decreased proliferating zone with round chondrocytes, scarce matrices and reduced proteoglycan aggregates. These mice had short, sparse chondroitin sulfate chains caused by a defect in chondroitin sulfate biosynthesis. We also identified that loss-of-function mutations in human SLC35D1 cause Schneckenbecken dysplasia, a severe skeletal dysplasia. Our findings highlight the crucial role of NSTs in proteoglycan function and cartilage metabolism, thus revealing a new paradigm for skeletal disease and glycobiology.     

Severe neurologic manifestations from cervical spine instability in spondylo-megaepiphyseal-metaphyseal dysplasia

Spondylo-megaepiphyseal-metaphyseal dysplasia (SMMD; OMIM 613330) is a dysostosis/dysplasia caused by recessive mutations in the homeobox-containing gene, NKX3-2 (formerly known as BAPX1). Because of the rarity of the condition, its diagnostic features and natural course are not well known. We describe clinical and radiographic findings in six patients (five of which with homozygous mutations in the NKX3-2 gene) and highlight the unusual and severe changes in the cervical spine and the neurologic complications. In individuals with SMMD, the trunk and the neck are short, while the limbs, fingers and toes are disproportionately long. Radiographs show a severe ossification delay of the vertebral bodies with sagittal and coronal clefts, missing ossification of the pubic bones, large round "balloon-like" epiphyses of the long bones, and presence of multiple pseudoepiphyses at all metacarpals and phalanges. Reduced or absent ossification of the cervical vertebrae leads to cervical instability with anterior or posterior kinking of the cervical spine (swan neck-like deformity, kyknodysostosis). As a result of the cervical spine instability or deformation, five of six patients in our series suffered cervical cord injury that manifested clinically as limb spasticity. Although the number of individuals observed is small, the high incidence of cervical spine deformation in SMMD is unique among skeletal dysplasias. Early diagnosis of SMMD by recognition of the radiographic pattern might prevent of the neurologic complications via prophylactic cervical spine stabilization.     

Somatostatin receptors are restricted to a subpopulation of osteoblast-like cells during endochondral bone formation.

Specific binding sites for the peptide hormone somatostatin have previously been demonstrated in long bones from neonatal rats. In the present study, the distribution of somatostatin receptors during embryonic bone formation has been investigated using the stable radioiodinated somatostatin analogue, SDZ 204-090. Somatostatin receptors in rat long bones were first detectable at the time of invasion of the cartilage model by osteogenic cells. Initially, receptors were detectable throughout the region occupied by osteogenic cells. As bone growth proceeded, however, receptors were restricted to the region of most recent invasion of the hypertrophic cartilage, where osteoid had not yet been deposited. In vivo labelling studies in neonatal rats were carried out to identify the cells bearing somatostatin receptors. Receptors were present in a restricted region of the metaphysis, immediately adjacent to the hypertrophic cartilage. Chondrocytes, osteoclasts, and mature osteoblasts were not labelled by the radioligand. The labelled cells were often apposed to remnants of cartilage matrix and stained positively for the osteoblast marker, alkaline phosphatase. Thus the cells with specific somatostatin-binding sites were probably osteoblast precursor cells. Specific binding was detectable in all endochondral bones examined, including those of the skull, but no specific binding was found in the membrane bones of the skull. These data suggest that somatostatin is involved in the regulation of osteoblast differentiation during endochondral bone formation.     

Lethal short limb dwarfism with dysmorphic face, omphalocele and severe ossification defect: Piepkorn syndrome or severe "boomerang dysplasia"?

The authors report a case of lethal neonatal dwarfism characterized by striking micromelia, fused rudimentary and supernumerary digits, large, soft head, pronounced hypertelorism, protruding eyes set laterally, enormous omphalocele and severe deficiency of tubular bone and spine ossification. Histologic examination showed lack of ossification of the cartilaginous anlage of many tubular bones. The cartilage had irregularly distributed chondrocytes. The matrix contained hypocellular and degenerated areas with scattered large chondrocytes. In a few bones a very disorganized growth cartilage was present. The case is similar to that described by Piepkorn et al. (1977) and may represent a severe form of "boomerang dysplasia" (Kozlowski et al., 1981; Tenconi et al., 1983; Kozlowski et al., 1985; Winship et al., 1990).