Mesodermal Defects Research Articles

ОСОБЕННОСТИ КЛИНИЧЕСКИХ ПРОЯВЛЕНИЙ ПРИ МАЛЬФОРМАЦИИ КИАРИ 0, 1 И «ПОГРАНИЧНОГО» ТИПОВ

Introduction. Introduction of advanced neuroimaging methods has made it possible to identify subtle structural features of the posterior cranial fossa and craniovertebral junction, as well as the dislocation of cerebellar tonsils into the foramen magnum, which have clinically overt and subclinical forms. Aim: To study the clinical manifestation features of Chiari type 0, 1, and “borderline” malformations. Materials and Methods. For literature analysis, the sources were used from international databases, such as Web of Science, Scopus, and PubMed, and the Russian library system, eLibrary. Results and Discussion. The most common pathology of the posterior cranial fossa is Chiari type 1 malformation associated with a mesodermal defect and with discrepancies between the sizes of the posterior cranial fossa and the neural structures that fill it. To assess the Chiari malformation grade, it is advisable to specify the dislocation grades of cerebellar tonsils. There is a common classification of cerebellar tonsil dislocations, in which the dislocation grade 1 of cerebellar tonsils is characterized by the descent of cerebellar tonsils below the foramen magnum level; grade 2 is inherent in dislocation of the cerebellar tonsils down to the C2 vertebra level in combination with displacing the pons and medulla oblongata below the Twining line. Grade 3 dislocation of the cerebellar tonsils is where the cerebellum tonsil displacement is combined with intracranial hypertension. In case of the degree 4 dislocation of the cerebellar tonsils, cerebellar hypoplasia is observed, accompanied by a displacement of the medulla oblongata. The occurrence of syringomyelia in Chiari type 0 malformation is associated with liquor dynamic disorders in the craniovertebral junction region; the similar liquor circulation disorders are detected in Chiari type 1 malformation. Chiari type 1 and “borderline”- type malformations manifest as persistent cranialgia, pain in the cervical spine, otoneurologic and visual disorders, respiratory, psychological, and cognitive disorders, damage to the cerebellar and stem structures of the brain, damage to the spinal cord, and other, more rare signs of damage to the central nervous system. Conclusions. Thus, it is necessary to further study the features of developing clinical symptoms in Chiari type 1, 0, and “borderline” malformations to assess the changes in the course of the disease and select an adequate treatment strategy.

Functional and morphological changes in hypoplasic posterior fossa

BackgroundThe knowledge of the development and the anatomy of the posterior cranial fossa (PCF) is crucial to define the occurrence and the prognosis of diseases where the surface and/or the volume of PCF is reduced, as several forms of craniosynostosis or Chiari type I malformation (CIM). To understand the functional and morphological changes resulting from such a hypoplasia is mandatory for their correct management. The purpose of this article is to review the pertinent literature to provide an update on this topic.MethodsThe related and most recent literature addressing the issue of the changes in hypoplasic PCF has been reviewed with particular interest in the studies focusing on the PCF characteristics in craniosynostosis, CIM, and achondroplasia.Results and conclusionsIn craniosynostoses, namely, the syndromic ones, PCF shows different degrees of hypoplasia, according to the different pattern and timing of early suture fusion. Several factors concur to PCF hypoplasia and contribute to the resulting problems (CIM, hydrocephalus), as the fusion of the major and minor sutures of the lambdoid arch, the involvement of the basal synchondroses, and the occlusion of the jugular foramina. The combination of these factors explains the variety of the clinical and radiological phenotypes. In primary CIM, the matter is complicated by the evidence that, in spite of impaired PCF 2D measurements and theories on the mesodermal defect, the PCF volumetry is often comparable to healthy subjects. CIM is revealed by the overcrowding of the foramen magnum that is the result of a cranio-cerebral disproportion (altered PCF brain volume/PCF total volume). Sometimes, this disproportion is evident and can be demonstrated (basilar invagination, real PCF hypoplasia); sometimes, it is not. Some recent genetic observations would suggest that CIM is the result of an excessive growth of the neural tissue rather than a reduced growth of PCF bones. Finally, in achondroplasia, both macrocephaly and reduced 2D and 3D values of PCF occur. Some aspects of this disease remain partially obscure, as the rare incidence of hydrocephalus and syringomyelia and the common occurrence of asymptomatic upper cervical spinal cord damage. On the other hand, the low rate of CIM could be explained on the basis of the reduced area of the foramen magnum, which would prevent the hindbrain herniation.

Anonychia Congenita in a Young Boy - A Rare Entity

Congenital anonychia in isolated form is a rare anomaly in which there is absence of nails of fingers and toes since birth. Other ectodermal and mesodermal defects in the body are absent. Here, we report a case of 16 year old male having rare congenital disorder anonychia in his hands and feet except in little finger of right hand, lateral two digits of right foot and thumbs of both hands with deformed nails. All other systemic examinations were normal. His parents and siblings were normal as were the second degree relatives.

Deletion of the Dishevelled family of genes disrupts anterior-posterior axis specification and selectively prevents mesoderm differentiation

The Dishevelled proteins transduce both canonical Wnt/β-catenin and non-canonical Wnt/planar cell polarity (PCP) signaling pathways to regulate many key developmental processes during embryogenesis. Here, we disrupt both canonical and non-canonical Wnt pathways by targeting the entire Dishevelled family of genes (Dvl1, Dvl2, and Dvl3) to investigate their functional roles in the early embryo. We identified several defects in anterior-posterior axis specification and mesoderm patterning in Dvl1+/−; Dvl2−/−; Dvl3−/− embryos. Homozygous deletions in all three Dvl genes (Dvl TKO) resulted in defects in distal visceral endoderm migration and a complete failure to induce mesoderm formation. To identify potential mechanisms that lead to the defects in the developmental processes preceding gastrulation, we generated Dvl TKO mouse embryonic stem cells (mESCs) and compared the transcriptional profile of these cells with wild-type (WT) mESCs during germ lineage differentiation into 3D embryoid bodies (EBs). While the Dvl TKO mESCs displayed similar morphology, self-renewal properties, and minor transcriptional variation from WT mESCs, we identified major transcriptional dysregulation in the Dvl TKO EBs during differentiation in a number of genes involved in anterior-posterior pattern specification, gastrulation induction, mesenchyme morphogenesis, and mesoderm-derived tissue development. The absence of the Dvls leads to specific down-regulation of BMP signaling genes. Furthermore, exogenous activation of canonical Wnt, BMP, and Nodal signaling all fail to rescue the mesodermal defects in the Dvl TKO EBs. Moreover, endoderm differentiation was promoted in the absence of mesoderm in the Dvl TKO EBs, while the suppression of ectoderm differentiation was delayed. Overall, we demonstrate that the Dvls are dispensable for maintaining self-renewal in mESCs but are critical during differentiation to regulate key developmental signaling pathways to promote proper axis specification and mesoderm formation.

Hedgehog–FGF signaling axis patterns anterior mesoderm during gastrulation

The mechanisms used by embryos to pattern tissues across their axes has fascinated developmental biologists since the founding of embryology. Here, using single-cell technology, we interrogate complex patterning defects and define a Hedgehog (Hh)-fibroblast growth factor (FGF) signaling axis required for anterior mesoderm lineage development during gastrulation. Single-cell transcriptome analysis of Hh-deficient mesoderm revealed selective deficits in anterior mesoderm populations, culminating in defects to anterior embryonic structures, including the pharyngeal arches, heart, and anterior somites. Transcriptional profiling of Hh-deficient mesoderm during gastrulation revealed disruptions to both transcriptional patterning of the mesoderm and FGF signaling for mesoderm migration. Mesoderm-specific Fgf4/Fgf8 double-mutants recapitulated anterior mesoderm defects and Hh-dependent GLI transcription factors modulated enhancers at FGF gene loci. Cellular migration defects during gastrulation induced by Hh pathway antagonism were mitigated by the addition of FGF4 protein. These findings implicate a multicomponent signaling hierarchy activated by Hh ligands from the embryonic node and executed by FGF signals in nascent mesoderm to control anterior mesoderm patterning.

Hox13 genes are required for mesoderm formation and axis elongation during early zebrafish development.

The early vertebrate embryo extends from anterior to posterior due to the addition of neural and mesodermal cells from a neuromesodermal progenitor (NMp) population located at the most posterior end of the embryo. In order to produce mesoderm throughout this time, the NMps produce their own niche, which is high in Wnt and low in retinoic acid. Using a loss-of-function approach, we demonstrate here that the two most abundant Hox13 genes in zebrafish have a novel role in providing robustness to the NMp niche by working in concert with the niche-establishing factor Brachyury to allow mesoderm formation. Mutants lacking both hoxa13b and hoxd13a in combination with reduced Brachyury activity have synergistic posterior body defects, in the strongest case producing embryos with severe mesodermal defects that phenocopy brachyury null mutants. Our results provide a new way of understanding the essential role of the Hox13 genes in early vertebrate development.This article has an associated 'The people behind the papers' interview.

Hydrometrocolpos - A Lower Mesodermal Defects Sequence

Hydrometrocolpos - A Lower Mesodermal Defects Sequence

Hydrometrocolpos: A Lower Mesodermal Defects Sequence

AbstractHydrometrocolpos is a rare congenital disorder, which can present prenatally or after birth. It can be isolated or associated with other abnormalities. The abnormalities associated with hydrometrocolpos can be primary or secondary. Primary abnormalities arise from disruption of embryological processes while secondary abnormalities arise from the pressure effects of the distended vagina and uterus on adjacent organs. An analysis of autopsy findings of four cases of hydrometrocolpos at our center has shown a nonrandom association of certain congenital abnormalities. These abnormalities involve structures arising from the infraumbilical intraembryonic mesoderm. A primary developmental failure or secondary disruption of normally formed tissues results in this condition called lower mesodermal defects sequence. Identification of this condition is important in prognostication and counseling parents.

PIAS-like protein Zimp7 is required for the restriction of the zebrafish organizer and mesoderm development

The Zmiz2 (Zimp7) protein and its homolog Zmiz1 (Zimp10) were initially identified in humans as androgen receptor co-activators. Sequence analysis revealed the presence of an SP-RING/Miz domain, which is highly conserved in members of the PIAS family and confers SUMO-conjugating activity. Zimp7 has been shown to interact with components of the Wnt/β-Catenin signaling pathway and with Brg1 and BAF57, components of the ATP-dependent mammalian SWI/SNF-like BAF chromatin-remodeling complexes.In this work, we analyze the role of zygotic Zimp7 in zebrafish development. We describe evidence indicating that Zimp7 is required for mesoderm development and dorsoventral patterning. Morpholino-mediated reduction of zygotic Zimp7 produced axial mesodermal defects that were preceded by up-regulation of organizer genes such as bozozok, goosecoid and floating head at the onset of gastrulation and by down-regulation of the ventral markers vox, vent and eve1 indicating loss of the ventrolateral mesoderm. Consistently, embryos overexpressing zimp7 RNA exhibited midline defects such as loss of forebrain and cyclopia accompanied by transcriptional changes directly opposite of those found in the morphants. In addition, the patterning of ventralized embryos produced by the overexpression of vox and vent was restored by a reduction of Zimp7 activity. Altogether, our findings indicate that Zimp7 is involved in transcriptional regulation of factors that are essential for patterning in the dorsoventral axis.

A case of VACTERL and non-VACTERL association without the "V and L"

VACTERL is a cluster of congenital malformations based on the non-random association of various congenital malformations in a single patient. Here “V” denotes vertebral defects or vascular anomalies (single umbilical artery), “A” anal atresia, “C” cardiac abnormalities, “TE” tracheoesophageal fistula, “R"renal (kidney) abnormalities and “L” for limb anomalies) It is called an association, rather than a syndrome because the complications are not pathogenetically related, tend to occur more frequently than expected and are thought to be linked to embryonic mesodermal defects. Studies have reported the coexistence of various other congenital malformations such as respiratory, cerebral anomalies, which are frequently referred as non-VACTERL-type of associations. Diagnosis of VACTERL association is done only when at least three of the above mentioned congenital malformations are identified in a patient. Although 80% of these cases have vertebral defects, our case is unique as patient does not have one of the commonest occuring association i.e., vertebral anomalies, but has all other associations and an additional non VACTERL brain anomaly, hitherto unreported in the literature. The other highlight of this case is although reports say that VACTERL babies with ipsilateral renal disorder have the same side limb defects, our case has a renal anomaly with no limb anomaly. Finally VACTERL and non VACTERL association was considered in our patient in view of ventricular septal defect, tracheo esophageal fistula, anal atresia, renal anomaly, seizure disorder and global developmental delay due to pontocerebellar hypoplasia.

Congenital Malalignment of the Fourth Toenail with Congenital Curved Nail of the Contralateral Fourth Toe

Dear Editor: A 3-month-old boy was presented with nail deformity on both of his fourth toenails. His left fourth toenail was not parallel to the distal phalanx, and right one had a curved shape (Fig. 1A, B). Both had been observed since birth. He had no family history or suspicious past history, such as trauma. Accompanied abnormalities were not observed. Radiologic examination of both feet revealed an absence of bone deformity or soft tissue defect (Fig. 2). We diagnosed his left fourth toenail as congenital malalignment, and the right one as congenital curved nail. Regular follow-up has been planned to prevent permanent deformity and complications. Fig. 1 (A) Laterally deviated left fourth toenail without any complication. (B) The nail of the right fourth toe curves plantarly. Fig. 2 Radiologic examination does not reveal any bony or soft tissue abnormalities. Congenital malalignment is defined as a condition of horizontal nail matrix deviation, compared with the longitudinal axis of the distal phalanx1. There are some etiologic hypotheses. Genetic factors, hereditary and embryological abnormalies and environmental factors such as intrauterine pressure on nails of the fetus have been thought as possible etiologic factors2. Congenital malalignment usually involves great toe nails; however, it may rarely involve other toenails and fingernails as well2. Although half of all patients have shown spontaneous improvement, the remainders suffer from severe complications, such as ingrown nail, onychogryphosis and persistent nail bed dystrophy3. Therefore, we decided to conduct regular follow-up of the patient until 2 years old. If his nail disorder persists, surgical intervention will be needed as a definite treatment. Baran and Haneke2 invented a surgical method, consisting of periungual wedge resection and rotation of the wedge-resected flap parallel to the distal phalanx. A modified surgical method has recently been tested to reduce proximal nail fold damage. Congenital curved nail of the fourth toe is characterized by a plantarly curved nail plate, which is parallel to the longitudinal axis of the distal phalanx. Actually, it is secondary nail deformity caused by congenital hypoplasia or loss of the distal phalanx4. However, similar to our case, some cases without underlying bony or soft tissue defect have been reported5. There have been no published case reports of congenital curved nail, which has involved other than the fourth toenail. Therefore, it is called congenital curved nail of the fourth toe. However, recently we experienced a case with congenital curved nail involving the bilateral second, third and fourth toenails; although it has not been published yet. It is thought that congenital curved nail can also be developed in other toenails except for the fourth nail. On the other hand, other disorders of fingernails and toenails are not accompanied with congenital curved nail, because it is thought to be a mesodermal defect, not an ectodermal defect4. Because of the underlying defects of the bone or soft tissue, definite treatment is very difficult. Therefore, conservative treatments such as avoiding trauma are recommended for the alleviation of onycholysis and further nail dystrophy. Due to low prevalence of congenital malalignment of the toenail and congenital curved nail of the fourth toenail, this report is meaningful. In addition, it presents the first case that combines these two nail disorders concurrently in one patient.

The association between prune belly syndrome and dental anomalies: a case report

BackgroundPrune belly syndrome is a rare condition produced by an early mesodermal defect that causes abdominal abnormalities. However, the literature indicates that disturbances related to ectodermal development may also be present. This is the first case report in the literature to suggest that dental abnormalities are part of the broad spectrum of clinical features of prune belly syndrome. Because the syndrome causes many serious medical problems, early diagnosis of abnormalities involving the primary and permanent dentitions are encouraged.Case presentationThe authors report the clinical case of a 4-year-old Caucasian boy with prune belly syndrome. In addition to the triad of abdominal muscle deficiency, abnormalities of the gastrointestinal and urinary tracts, and cryptorchidism, a geminated mandibular right central incisor, agenesis of a mandibular permanent left incisor, and congenitally missing primary teeth (namely, the mandibular right and left lateral incisors) were noted.ConclusionThis original case report about prune belly syndrome highlights the possibility that dental abnormalities are a part of the broad spectrum of clinical features of the syndrome. Therefore, an accurate intra-oral clinical examination and radiographic evaluation are required for patients with this syndrome in order to provide an early diagnosis of abnormalities involving the primary and permanent dentitions.

Morning glory disc anomaly with contractile movements

Morning glory disc anomaly is a rare malformation characterized by an ectasia of the posterior pole of the fundus involving the optic disc. Embryologically, there are some theories for its pathogenesis, including primary mesenchymal abnormality, defective closure of the embryonic fissure, and basic defect of mesoderm combined with dynamic disturbance between the relative growth of mesoderm and ectoderm. However, the exact mechanism is still unknown. It is usually unilateral and occurs more frequently in women. Visual acuity is 20/200 or worse in 90 % of cases, but it can be as good as 20/20 [1]. Retinal detachment occurs in 30 % of cases, and many are non-rhegmatogenous with subretinal fluid accumulating around the optic disc [2]. It is usually non-contractile, but in extremely rare cases, it can exhibit contractile movements [3–5]. Here we present a contractile morning glory disc anomaly case with a video recording of the contractions.

A Fetus with Hemifacial Microsomia and Sirenomelia. The Same Mesodermal Defect Spectrum?

Sirenomelia is the most severe malformation complex affecting the human caudal pole, although its etiology is unclear, a primary defect of blastogenesis has been proposed. Studies consider sirenomelia as the most severe form of caudal dysgenesis, VACTERL association, or axial mesodermal dysplasia, although others still support the idea of a different pathologic entity. We report the prenatal, clinical, and pathologic features of a fetus with cleft lip and palate, microtia, cardiac, renal and intestinal malformations, radial aplasia, and sirenomelia. Karyotype, chromosomal breakage studies, and SHH sequence analysis were normal. The occurrence of cephalic, midline-paramedial, and caudal malformations in the same patient imply the diagnosis of hemifacial microsomia and sirenomelia. These entities are part of the same mesodermal malformation spectrum and the clinical presentation depends on environmental and genetic interactions in embrionic development. Future clinical and genome wide studies will help to better delineate this spectrum.

Role of lbx2 in the noncanonical Wnt signaling pathway for convergence and extension movements and hypaxial myogenesis in zebrafish

It has been suggested that mouse lbx1 is essential for directing hypaxial myogenic precursor cell migration. In zebrafish, the expression of lbx1a, lbx1b, and lbx2 has been observed in pectoral fin buds. It has also been shown that knocking down endogenous lbx2 in zebrafish embryos diminishes myoD expression in the pectoral fin bud. However, downstream lbxs signals remain largely unexplored. Here, we describe a previously unknown function of zebrafish lbx2 (lbx2) during convergent extension (CE) movements. The abrogation of the lbx2 function by two non-overlapping morpholino oligonucleotides (MOs) resulted in the defective convergence and extension movements in morphants during gastrulation. Our transplantation studies further demonstrated that the overexpression of lbx2 autonomously promotes CE movements. Expression of wnt5b is significantly reduced in lbx2 morphants. We have demonstrated that application of the wnt5b MO, a dominant-negative form of disheveled (Dvl) and a chemical inhibitor of Rho-associated kinase Y27632 in zebrafish embryos have effects reminiscent that are of the CE and hypaxial myogenesis defects observed in lbx2 morphants. Moreover, the CE and hypaxial mesoderm defects seen in lbx2 morphants can be rescued by co-injection with wnt5b or RhoA mRNA. However, this reduced level of active RhoA and hypaxial myogenesis defects in the embryos injected with the dominant-negative form of Dvl mRNA cannot be effectively restored by co-injection with lbx2 mRNA. Our results suggest that the key noncanonical Wnt signaling components Wnt5, Dvl, and RhoA are downstream effectors involved in the regulative roles of lbx2 in CE movement and hypaxial myogenesis during zebrafish embryogenesis.

Cantrell‘s Syndrome

Cantrell s syndrome is characterized by: 1) Omphalocele 2) Sternal cleft 3) Anterior diaphragmatic hernia 4) Ectopia cordis 5) Intracardiac defects With an incidence of 5 to 8 cases per million of newborn babies, this syndrome is caused by mesodermal defects in early stages of the embrionary period. There are two ways of presentation: complete and incomplete. The incomplete way is when the heart is covered by skin, pericardium or both of them. In the complete way, the sternum is absent or it has a wide defect. There is no parietal pericardium and the heart is totally out of the thorax with its apex upwards and there is an important reduction in the size of the thoracic cavity. Generally, with omphalocele. 80% of the cases with incomplete way present congenital heart defect and in the complete way this percentage is 100%. Truncoconal abnormalities are the most usual. The studied case had interventricular communication (IVC) and the emergence of the great vessels was difficult to observe.

Chronic middle foot pain in a patient with a swollen leg: diagnosis and discussion

Klippel-Trenaunay-Weber or simply Klippel-Trenaunay syndrome (KTS) also known as osteoangiohypertrophy syndrome or nevus vasculosus hypertrophicus is a rare congenital non-inheritable venous disorder of unknown origin. A classical symptom triad of port-wine stain, varicosis, and limb hypertrophy was first described by the two French physicians Maurice Klippel and Paul Trenaunay in 1900 [1]. The etiology of KTS is still not determined. Klippel and Trenaunay speculated that a spinal cord abnormality might be the cause of observed symptoms. Other authors believe that atresia of the deep leg veins or developmental mesodermal defect could be the underlying cause [2]. Current findings suggest that KTS is a result of mutation of an angiogenic factor gene [3]. Diagnosis is usually based on the presence of at least two classic symptoms at birth or in early childhood. Cutaneous manifestations are red to purplish in color and can be found on any part of the body in 98% of patients [4]. They are vascular malformation–ectatic, thin-walled capillaries in the dermis. Varicosis is found in 72% of the KTS-affected population [4]. The deep venous system of an affected limb might also be involved. Of high importance are visceral vascular malformations as they can cause severe hemorrhages. Lymphatic system involvement in the form of malformations is reported in 11% of patients [4]. Jacob et al. found that 67% of KTS patients present with a limb hypertrophy limited to one leg but more limbs and head or trunk might also be involved [4]. In an overwhelming majority of cases, girth and/or length of involved extremity is increased, but decrease of length and width have also been reported [5]. The limb enlargement develops because of soft tissue hypertrophy with or without bone hypertrophy. Associated findings include macrodactyly, syndactyly, and polydactyly [6]. Affected bones are elongated and show cortical thickening. An imaging feature of advanced stages is osteoporotic-like changes owing to intraosseous vascular malformations as seen in our patient [7]. In many patients there is no treatment needed, although compression stockings are recommended for all of them [8]. Skin care is advised to avoid cellulitis. In mature patients with leg length difference of more then 2 cm, surgical shortening of the affected limb might be considered. Superficial as well as deep vascular malformations might be treated by laser therapy, excision, cryotherapy, sclerosis, and ligation. In the presented patient, osteoangiohypertrophy syndrome of left leg has been diagnosed in childhood. Because of chronic foot pain, a radiograph was performed that showed phleboliths, osteopenia of the first to third metatarsal and The case presentation can be found at doi:10.1007/s00256-011-1237-9.

Neuroradiological diagnosis of Chiari malformations

Chiari malformations 1, 2, 3 represent different degrees of herniation of posterior fossa content into the cervical canal (Chiari 1 and 2), or through an upper-cervical meningocele (Chiari 3), whereas Chiari 4 anomaly consists of hypoplasia of the cerebellum. Chiari 1 malformation (CM1) is the commonest anomaly; it is probably related to a mesodermal defect that create a congenitally small posterior fossa, subsequent overcrowding of its contents and herniation through the foramen magnum. The diagnosis of CM1 is based on the demonstration of the downward displacement and particular shape of the cerebellar tonsils into the upper cervical spinal canal associated with obliteration of the subarachnoid spaces at the level of the foramen magnum. MRI has a fundamental role in the correct identification of the anatomical aspects of this malformation and associated anomalies and represents the imaging modality of choice.

Posterior cranial fossa morphometry in symptomatic adult Chiari I malformation patients: Comparative clinical and anatomical study

Background and objectives The cerebellar tonsillar herniation occurring in Chiari malformation Type I (CMI) mainly results from overcrowding of a normally developing hindbrain within a primary small posterior cranial fossa (PCF) due to an anomaly in the embryological development of the occipital bone. In the present study, the lengths of PCF parameters were studied in adult CMI patients. Patients and methods The authors retrospectively examined 15 adult patients with CMI. Multiple measurements were made on magnetic resonance images (MRIs). The results were compared with the findings in 25 controls and 30 dry skulls. Results Length of the neural structures did not significantly differ between the CMI and the control groups. The average length of the basiocciput was significantly shorter in the CMI group as compared with the control group. The mean length of the supraocciput was significantly shorter and the average diameter of the foramen magnum was significantly longer in the CMI group when compared to the control group and dry skulls. Conclusions The morphometric data suggest that, in CMI, a hypoplastic occipital bone, possibly due to the paraxial mesodermal defect of the parachordal plate, causes overcrowding in PCF, which contains the normally developed neural structures.

Dentinogenesis Imperfecta – “A Hereditary Developmental Disturbance of Dentin”

Dentinogenesis Imperfecta (DGI) is a genetic disorder of tooth development inherited in an autosomal, dominant way, characterized by the presence of translucent or opalescent dentin, resulting in discoloration (amber-like, bluish grey color) of the teeth. It is a mesodermal defect wherein the dental papilla of either or both the primary and secondary dentition is abnormal. This paper describes the dental findings in a family where the father (33 year old) and the son (3 year old) both showed the characteristic dental features of DGI I.