Feasibility of spheno-occipital synchondrosis fusion stages as an indicator for the assessment of maxillomandibular growth: A mixed longitudinal study.

OBJECTIVES: This study aimed to assess the relative growth rates (RGRs) of the maxilla and mandible at varying fusion stages of the spheno-occipital synchondrosis (SOS), thereby elucidating the potential of SOS stages in predicting maxillomandibular growth. MATERIALS AND METHODS: A total of 320 subjects (171 boys and 149 girls), aged 6 to 18 years, were retrospectively included. Each subject had a minimum of two longitudinal cone-beam computed tomography (CBCT) images, with no more than one interval of SOS fusion stage change between the two scans. Subjects were categorized based on their SOS fusion stages and genders. The RGRs of the maxilla and mandible at various SOS fusion stages were measured and compared using longitudinal CBCT images. RESULTS: Significant statistical differences were observed in maxillomandibular RGRs across various SOS fusion stages. In girls, the sagittal growth of the maxilla remained stable and active until SOS 3, subsequently exhibited deceleration in SOS 4-5 (compared to SOS 3-4, P < .05) and continued to decrease in SOS 5-6. Whereas in boys, the sagittal growth of the maxilla remained stable until SOS 4, and a deceleration trend emerged starting from SOS 5 to 6 (P < .01 compared to SOS 4-5). Mandibular growth patterns in both genders exhibited a progression of increasing-accelerating-decelerating rates from SOS 2 to 6. The highest RGRs for total mandibular length were observed in SOS 3-4 and SOS 4-5. CONCLUSION: Spheno-occipital synchondrosis fusion stages can serve as a valid indicator of maxillomandibular growth maturation.

A Computed Tomographic Analysis of Spheno-Occipital Synchondrosis Ossification for Age Estimation in a Sample of Egyptians.

ABSTRACT: The aim of the present work was to create statistically quantified age estimation standards based on spheno-occipital synchondrosis (SOS) fusion state as visualized in computed tomography in Egyptians. The study included 208 Egyptians between the ages of 5 and 30 years (117 male and 90 female participants). Spheno-occipital synchondrosis was visualized in a midsagittal view in a neutral head position. Degree of ossification of SOS was assessed using a 4-stage system. Interobserver agreement and intraobserver agreement were almost perfect with Cohen κ values of 0.863 and 0.983, respectively. The mean ages of complete fusion (stage 3) were 20.36 ± 3.11 and 20.94 ± 4.06 years in male and female participants, respectively. Nonfusion (stage 0) was observed up to 15 and 13 years in male and female participants, respectively. Complete fusion occurred as early as 15 and 13 years in male and female participants, respectively. All subjects with nonfused SOS were minors (<18 years). A total of 87.9% of male participants and 85.3% of female participants with completely fused SOS were legally adults (≥18 years). Significant regression models were formulated to predict age from SOS fusion stage (adjusted R2 = 0.779 for male participants and 0.780 for female participants). Regression models predicted that male and female participants 18 years or older with 96.30% and 95.59% accuracy, respectively.

Occipital hemi-bun development and shape covariation in a longitudinal extant human growth sample.

OBJECTIVES: Although the homology of the Neanderthal occipital bun and anatomically modern human "hemi-bun" has long been debated, little is known about the developmental timing and patterning of these two patterns of prominent occipital squama convexity. In this study, occipital hemi-bun ontogeny and cranial shape covariation are assessed in a comparative extant human sample. MATERIALS AND METHODS: Two-dimensional geometric morphometric methods were used to investigate hemi-bun development in a longitudinal sample of growth study cephalograms representing extant human subjects predominantly of European ancestry. Subjects were each measured at three distinct age points, ranging from 3.0 to 20.4 years, and two-block partial least squares analysis was used to assess patterns of covariation between midsagittal occipital bone morphology and other aspects of craniofacial shape. RESULTS: Occipital hemi-bun morphology, when present, was found to develop early in ontogeny, in association with anteroposterior elongation of the frontal and parietal bones. No significant pattern of covariation was found between occipital hemi-bun shape and cranial/basicranial breadth, basicranial length, basicranial angle, or midfacial prognathism. DISCUSSION: This study suggests that the occipital hemi-bun, at least in this extant human population, should not be considered an independent trait, as its development is closely linked to shape variation in the frontal and parietal bones. Importantly, these results suggest that occipital hemi-bun morphology is not significantly influenced by basicranial morphology during development, but instead covaries with changes in midsagittal neurocranial vault shape.

Proposal of new regression formulae for the estimation of age in infant skeletal remains from the metric study of the pars basilaris.

In the context of physical and forensic anthropology, when a child's skeleton is damaged or in poor condition, which is common, many of the metric methods for the estimation of skeletal age cannot be used. In these circumstances, those more resistant bones, such as the pars basilaris, will be most useful. The aims of this study were to test existing methods for estimating skeletal age from the metric study of the pars basilaris and to propose new regression formulae. One hundred fourteen individuals aged between 5 months of gestation and 6 years were analyzed; seven measures were taken from each pars basilaris using a digital caliper. The chronological age was compared with the estimated age using the methods published by Fazekas and Kósa in 1978 and by Scheuer and MacLaughlin in 1994. New regression formulae are proposed, obtained by classical calibration, which include confidence intervals at 50 and 97.5 % to express the error. With both methods, significant differences were observed; the method of Fazekas and Kósa shows a tendency to underestimate the age, and the method of Scheuer and MacLaughlin tends to overestimate it. The proposed formulae represent a good tool for estimating age in many different contexts because they are relatively easy to apply, although other analysis systems, such as Bayesian approach or geometric morphometry, offer more robust and effective results.

Clival canal and clival foramen development in the fetal and infant basioccipital.

PURPOSE: There is a paucity of research regarding both the development and the prevalence of the clival canal or clival foramen in fetuses. Reports that have examined child and adult populations have posited ideas for the development of the canal and foramen; however, they have done so in the absence of anatomical data from the fetal population. Therefore, the present study was performed to elucidate the development of the clival canal and foramen through the assessment of perinatal basioccipitals. METHODS: This study analyzed 104 basioccipital bones, 60 from fetuses and 44 from newborns and infants. Dorsal surfaces of basioccipitals were assessed for the presence of anatomical variation with particular attention to the presence of clival canals and foramina. Among cases in which the presence of a clival canal or clival foramen was suspected, cannulation was performed for verification. RESULTS: Of the 104 basioccipitals analyzed, 1 (0.96%) had a clival foramen. Clival canals were identified in seven basioccipitals (7:104; 6.73%), four of which were from fetuses. Trends in anatomical variations among basioccipitals were also identified and categorized. These categories were then evaluated relative to age in order to elucidate ontogeny. A model is presented to explain the development of the clival foramen, the clival canal, and the basioccipital, in general. CONCLUSIONS: The presence of a clival canal or foramen should be considered even among individuals of fetal age. The findings of this osteological study suggest that the clival canal and foramen develop around vascular structures and, therefore, signify vascular connections among nearby venous plexuses.

Postnatal Development of the Spheno-occipital Synchondrosis: A Histological Analysis.

The spheno-occipital synchondrosis (SOS) in cranial base is an important growth center for the craniofacial skeleton, and also is a guide rail for development of the maxilla, midface, and mandible. Previous studies showed that SOS may be a treatment target for youngsters with midfacial hypoplasia and small cranial vault secondary to craniosynostosis. However, most of studies about the SOS are based on imaging data. In this study, we try to explore the characteristics of postnatal development of the mouse SOS based on histological analysis. Our findings showed that the width of the SOS in mice were gradually decreased from newborn mice to adult mice, and the SOS cartilage was gradually became small, then almost completely ossificated in adult mice. The resting and proliferative layers in SOS cartilage were gradually decreased, and almost only hypertrophic chondrocytes while no resting and proliferative layer chondrocytes in adult mice. The proliferative ability of SOS chondrocytes also gradually decreased. These findings will be of benefit for the further clinical treatment for patients with midfacial hypoplasia or small cranial vault secondary to craniosynostosis. Further evidence-based research about the clinical implication is necessary in future.

The timing of spheno-occipital fusion in hominoids.

The degree of spheno-occipital fusion has been used to assign a relative age to dentally mature hominoid cranial specimens. However, a recent study of captive individuals (Poe: Am J Phys Anthropol 144 (2011) 162­165) concluded that fusion of the spheno-occipital suture in great ape taxa is of little utility for aging dentally mature individuals. In this contribution, I use dentally mature samples of extant hominoid taxa (Homo sapiens, Pan troglodytes schweinfurthii, Gorilla gorilla gorilla, Pongo pygmaeus pygmaeus and Hylobates lar) to investigate a) the temporal relationship between spheno-occipital fusion and dental maturity, b) whether there is an association between the degree of spheno-occipital fusion and relative age, c) whether there are differences in relative timing of spheno-occipital fusion between taxa, and d) whether there are sex differences in the relative timing of spheno-occipital fusion. Results suggest that a) a substantial proportion of dentally mature wild-shot chimpanzee, gorilla and orang-utans have unfused or partially fused spheno-occipital synchondoses, b) there is an association between the degree of spheno-occipital fusion and age, c) there are interspecific differences in the timing of spheno-occipital fusion, and d) there are significant sex differences in spheno-occipital fusion in chimpanzees, orang-utans and gibbons. Thus, contrary to previous work, degree of spheno-occipital fusion is a potentially useful indicator of relative maturity, especially in great ape taxa.

Ontogeny of the spheno-occipital synchondrosis in a modern Queensland, Australian population using computed tomography.

Due to disparity regarding the age at which skeletal maturation of the spheno-occipital synchondrosis occurs in forensic and biological literature, this study provides recalibrated multislice computed tomography (MSCT) age standards for the Australian (Queensland) population, using a Bayesian statistical approach. The sample comprises retrospective cranial/cervical MSCT scans obtained from 448 males and 416 females aged birth to 20 years from the Skeletal Biology and Forensic Anthropology Research Osteological Database. Fusion status of the synchondrosis was scored using a modified six-stage scoring tier on an MSCT platform, with negligible observer error (κ = 0.911 ± 0.04, intraclass correlation coefficient = 0.994). Bayesian transition analysis indicates that females are most likely to transition to complete fusion at 13.1 years and males at 15.6 years. Posterior densities were derived for each morphological stage, with complete fusion of the synchondrosis attained in all Queensland males over 16.3 years of age and females aged 13.8 years and older. The results demonstrate significant sexual dimorphism in synchondrosis fusion and are suggestive of intrapopulation variation between major geographic regions in Australia. This study contributes to the growing repository of contemporary anthropological standards calibrated for the Queensland milieu to improve the efficacy of the coronial process for medicolegal death investigation. As a stand-alone age indicator, the basicranial synchondrosis may be consulted as an exclusion criterion when determining the age of majority that constitutes 17 years in Queensland forensic practice.

The effects of tissue-non-specific alkaline phosphatase gene therapy on craniosynostosis and craniofacial morphology in the FGFR2C342Y/+ mouse model of Crouzon craniosynostosis.

OBJECTIVES: Craniosynostosis, the premature fusion of cranial bones, has traditionally been described as a disease of increased bone mineralization. However, multiple mouse models of craniosynostosis display craniosynostosis simultaneously with diminished cranial bone volume and/or density. We propose an alternative hypothesis that craniosynostosis results from abnormal tissue mineralization through the downregulation of tissue-non-specific alkaline phosphatase (TNAP) enzyme downstream of activating mutations in FGFRs. MATERIAL AND METHODS: Neonatal Crouzon (FGFRC342Y/+) and wild-type (FGFR+/+) mice were injected with lentivirus to deliver a recombinant form of TNAP. Mice were sacrificed at 4 weeks postnatal. Serum was collected to test for alkaline phosphatase (AP), phosphorus, and calcium levels. Craniofacial bone fusion and morphology were assessed by micro-computed tomography. RESULTS: Injection with the TNAP lentivirus significantly increased serum AP levels (increased serum AP levels are indicative of efficient transduction and production of the recombinant protein), but results were variable and dependent upon viral lot and the litter of mice injected. Morphological analysis revealed craniofacial form differences for inferior surface (p=0.023) and cranial height (p=0.014) regions between TNAP lentivirus-injected and vehicle-injected Crouzon mice. With each unit increase in AP level, the odds of lambdoid suture fusion decreased by 84.2% and these results came close to statistical significance (p=0.068). CONCLUSION: These results suggest that TNAP deficiency may mediate FGFR2-associated craniosynostosis. Future studies should incorporate injection of recombinant TNAP protein, to avoid potential side effects and variable efficacy of lentiviral gene delivery.

Long-term morphological outcomes in nonsyndromic sagittal craniosynostosis: a comparison of 2 techniques.

Correction of scaphocephaly is one of the principle goals of surgery in sagittal craniosynostosis. Reported relapse in head shape after surgery and continued head growth into late adolescence underscores the need for long-term outcomes to be considered when comparing between different surgical approaches in this condition; yet there are relatively few reports of results to 5 years and beyond in the literature. Therefore, a retrospective review was performed of the anthropometric data of 224 patients with sagittal craniosynostosis who underwent primary surgery between 1994 and 2012. During this period, patients underwent either a modified strip craniectomy (MSC) or calvarial remodeling (CR) procedure. Sixty-two patients were treated by MSC and followed up for a mean of 44 months. One hundred sixty-two patients had CR, with follow-up for a mean of 45 months. Overall, 90 patients were seen up to 5 years, and 47 patients to 9 years or more after surgery. The cephalic index (CI) of MSC-treated patients improved from a mean of 67.0 to 72.7, with 31% achieving a CI greater than 75 at one year. Calvarial remodeling was significantly more effective at correcting the scaphocephalic deformity. Patients treated with CR improved from a mean CI of 66.7 to 76.1. Sixty-two percent of the patients achieved a CI greater than 75. In both groups, outcomes were stable throughout follow-up with no significant relapse up to 14 years after surgery.

Brief communication: timing of spheno-occipital closure in modern Western Australians.

The spheno-occipital synchondrosis is a craniofacial growth centre between the occipital and sphenoid bones-its ossification persists into adolescence, which for the skeletal biologist, means it has potential application for estimating subadult age. Based on previous research the timing of spheno-occipital fusion is widely variable between and within populations, with reports of complete fusion in individuals as young as 11 years of age and nonfusion in adults. The aim of this study is, therefore, to examine this structure in a mixed sex sample of Western Australian individuals that developmentally span late childhood to adulthood. The objective is to develop statistically quantified age estimation standards based on scoring the degree of spheno-occipital fusion. The sample comprises multidetector computed tomography (MDCT) scans of 312 individuals (169 male; 143 female) between 5 and 25 years of age. Each MDCT scan is visualized in a standardized sagittal plane using three-dimensional oblique multiplanar reformatting. Fusion status is scored according to a four-stage system. Transition analysis is used to calculate age ranges for each defined stage and determine the mean age for transition between an unfused, fusing and fused status. The maximum likelihood estimates for the transition from open to fusing in the endocranial half is 14.44 years (male) and 11.42 years (female); transition from fusion in the ectocranial half to complete fusion is 16.16 years (male) and 13.62 years (female). This study affirms the potential value of assessing the degree of fusion in the spheno-occipital synchondrosis as an indicator of skeletal age.

The spheno-occipital synchondrosis fuses prematurely in patients with Crouzon syndrome and midface hypoplasia compared with age- and gender-matched controls.

PURPOSE: Premature closure of the spheno-occipital synchondrosis (SOS) has been associated with midface hypoplasia in animal models and patients with specific forms of syndromic craniosynostosis. The present study aimed to characterize SOS fusion in patients with Crouzon syndrome. PATIENTS AND METHODS: A case-control study was performed in patients with Crouzon syndrome treated at the Children's Hospital of Philadelphia from 1984 to 2012. The cases included patients with Crouzon syndrome and at least 1 high-quality computed tomography (CT) scan in which SOS patency could be assessed. Age- and gender-matched control CT scans were identified for comparison. The patient age at the CT scan was evaluated as the predictor, with SOS patency identified as the outcome variable. Three independent reviewers with high inter-rater reliability graded the SOS patency as open, partially fused, or completely fused. The Wilcoxon rank sum test was used to compare the Crouzon group and the controls. RESULTS: During the study period, 30 patients were identified with Crouzon syndrome. A total of 24 patients, all with midface hypoplasia and with 112 cranial CT scans, met the inclusion criteria. Accordingly, 112 age- and gender-matched control CT scans were assessed. No patient in the control group had midface hypoplasia. Within the Crouzon group, the average age at complete closure (14.0 ± 3.4 years) evident on the CT scan was significantly younger than that in the control group (16.6 ± 2.2 years; P = .0152). The average age when the scans showed complete patency of the SOS in the Crouzon group (1.3 ± 1.1 years) was significantly younger than that in the control group (3.2 ± 2.3 years; P = .0001). CONCLUSIONS: The SOS closes significantly earlier in patients with Crouzon syndrome compared with age- and gender-matched controls. The strong statistical correlation supports premature closure of the SOS as a possible mechanistic contributor to midface hypoplasia.

Age estimation of immature human skeletal remains using the post-natal development of the occipital bone.

Whenever age cannot be estimated from dental formation in immature human skeletal remains, other methods are required. In the post-natal period, development of the skeleton provides alternative age indicators, namely, those associated with skeletal maturity of the cranium. This study wishes to document the age at which the various ossification centres in the occipital bone fuse and provide readily available developmental probabilistic information for use in age estimation. A sample of 64 identified immature skeletons between birth and 8 years of age from the Lisbon collection was used (females = 29, males = 35). Results show that fusion occurs first in the posterior intra-occipital synchondrosis and between the jugular and condylar limbs of the lateral occipital to form the hypoglossal canal (1-4 years), followed by the anterior intra-occipital (3-7 years). Fusion of the post-natal occipital does not show differences in timing between males and females. Relative to other published sources, this study documents first and last ages of fusion of several ossification centres and the posterior probabilities of age given a certain stage of fusion. Given the least amount of overlap in stages of fusion, the closure of the hypoglossal canal provides the narrowest estimated age with the highest probability of age.

The effect of naringin on early growth and development of the spheno-occipital synchondrosis as measured by the expression of PTHrP and Sox9--an in vitro model.

The aim of this study was to assess the effect of the flavonoid naringin on the growth of the spheno-occipital synchondrosis by quantifying the levels of expression of Sox9 and PTHrP in an in vitro mouse model. Fifty 1-day-old BALB/c mice were randomly assigned to experimental or control groups, and each group equally divided into five time frames (6, 24, 48, 72 and 168 hours). The mice were sacrificed with phenobarbitone sodium, and the spheno-occipital synchondroses dissected and cultured in control or experimental medium, with the experimental medium supplemented with 0.1 µm naringin. Sections of the specimens underwent immunohistochemical staining for Sox9 and PTHrP, and the amount of expression was quantified using true-colour RGB (red-green-blue) computer-assisted image-analysing system with digital imaging. Data analysis showed there was a significant increase of expression of Sox9 at 6 and 24 hours (P < 0.001) between experimental and control groups, however, there was no significant difference between the levels of expression of PTHrP between experimental and control groups at any of the time frames. There was a very weak correlation found in this study between the expression of PTHrP and Sox9. In conclusion, naringin enhances the growth of the spheno-occipital synchondrosis through over expression of Sox9. This is a successful in vitro model to study factors regulating the growth of the spheno-occipital synchondrosis.

Effects of induced precocious puberty on cranial growth in female Wistar rats.

This investigation examined the effects of pharmacologically induced precocious puberty on cranial growth in Wistar rats. Forty-eight female newborn Wistar rats were divided into two groups: a control group (C) and an experimental group (E), with four subgroups of six animals each. The time interval from birth until sacrifice differed between the subgroups, and was set at 30, 60, 90, and 120 days. An intramuscular single dose (300 µg) of steroid hormone danazol was administered on day 5 after birth, as a means of inducing precocious puberty. Alizarin (2 mg/100 g) was administered to three animals in each subgroup three days prior to sacrifice. Body mass and dates corresponding to the beginning of the oestrous cycle were recorded. Craniometric measurements were undertaken. Histological analysis using light and fluorescence microscopy was then carried out to qualitatively and quantitatively evaluate the spheno-occipital synchondrosis and to visualize bone deposition patterns. The results were analysed with a Student's t-test and analysis of variance. Precocious puberty was effectively induced and differences between groups denoted an earlier maturation in the experimental rats. In qualitative analysis, a significant increase of total synchondrosis width was noted only in group E60, in comparison with C60, and an increase in the E90 subgroup cortical bone width compared with the C90 subgroup. Histomorphometrically, a statistical difference between total width values of subgroups E60 (434.3 µm) and C60 (323.5 µm) was detected. However, body mass and macroscopic measurements did not show statistically significant differences. An appropriate model for studying bone growth associated with precocious puberty in Wistar female rats was not achieved using steroid hormone danazol, when evaluated at 30 day intervals.

Brief communication: Testing the usefulness of the basilar suture as a means to determine age in great ape skeletons.

A fused/closed basilar suture is usually treated as an indication of old age in great apes. A sample, drawn from a variety of sources, of known-aged captive great ape skeletons was analyzed to test the usefulness of using the basilar suture to categorize adult skeletons as either "adult" or "old adult". The state of closure of the basilar suture was examined in 30 chimpanzees, 19 gorillas, and 15 orangutans, all of known age. The results show that the basilar suture demonstrates a high level of uniformity in rate of closure and is closed at an early age in virtually all known-aged individuals. Thus, an old adult category most likely includes individuals who are, in fact, relatively young. This indicates that using the basilar suture as a means to classify individual skeletons as adult or old adult is very imprecise. The homogenous nature of basilar suture closure appears to prevent meaningful application of suture status for categorizing adult ape skeletons by age groups.

The mendosal suture.

PURPOSE: The knowledge regarding the mendosal suture is still on debate in the literature. Though reports of the closure of this childhood suture are variable, a few reports show the presence of the suture in the adults. This study was conducted to determine the occurrence and a better topographic location of the mendosal suture. METHODS: We used 129 dry skulls for this study. In the specimens, which were determined to have a mendosal suture, the morphometric traits of the mendosal suture and the angle between the mendosal suture line and lambdoidal suture line (α angle) were measured. RESULTS: We found mendosal suture on 18 specimens, 11 of them were bilateral and 7 were unilateral. The length of these sutures ranged from 10.4 to 23.8 mm on the right side and 10.8 to 31.6 mm on the left side, respectively. The angle between two suture lines ranged from 36 to 68° on the right side and 32 to 75° on the left side. CONCLUSIONS: We believe that, these data will be of use to clinicians in order to avoid any misinterpretation of the mendosal suture with cranial fractures.

A mixed longitudinal anthropometric study of craniofacial growth of Colombian mestizos 6-17 years of age.

The purpose of this study was to evaluate the craniofacial growth of Colombian mestizos. Four age cohorts, including a total of 458 children and adolescents (262 males and 216 females), were included in this mixed-longitudinal study. The cohorts were first measured at ages 6, 9, 12, and 15 and every year thereafter for 3 years. Eight anthropometric measurements were taken, including three cranial (head perimeter, head width, and head length), two craniofacial (maxillary and mandibular length), and three facial (face height, bizygomatic width, and bigonial width). Multilevel analyses showed that all dimensions increased between 6 and 17 years of age. The cranium grew less than the craniofacial, which in turn grew less than the facial dimensions. In addition, vertical dimensions showed more growth than antero-posterior dimensions, which in turn grew more than transverse dimensions. None of the measurement showed statistically significant growth differences between subjects with normal occlusion and Class I or Class II malocclusions. Males were generally larger than females and showed greater growth rates. Except for facial width, whose yearly velocities decreased regularly with age, an adolescent growth spurt was evident for most of the male measurements. Yearly velocities for females followed a simpler decelerating pattern. The results provide reference data for Colombian mestizos, for whom normative data of other ethnic groups are not applicable. While occlusion had little or no effect, there were gender differences, as well as important growth differences between cranial and facial measurements.

A novel anthropometric chart for craniofacial surgery.

Various indices and measurements of the growing cranial vault exist, but there is no single head-shape chart specific to craniofacial surgery. The authors have produced a reliable head-shape chart that will enable accurate charting of patients with craniosynostosis both in the preoperative and postoperative period.One thousand eighty-two participants were used to obtain normal anthropometric measurements, specifically the ear-to-ear measurement and the glabella-to-external occipital protuberance measurement. Both male and female participants aged 6 months to 25 years were used to obtain these measurements. These measurements were correlated with the cephalic index as described by Farkas according to the different age groups.A head-shape chart has been created for males and females using the normal ear-to-ear measurements and the cephalic index that define both qualitative and quantitative elements of the growing skull. Craniofacial surgeons may find this chart useful for managing patients with craniosynostosis. This chart is also useful in the assessment of how the skull grows after surgery.

Cervical vertebrae, cranial base, and mandibular retrognathia in human triploid fetuses.

On profile radiographs of adults, an association between fusions of cervical vertebrae, deviations in the cranial base and mandibular retrognathia has been documented radiographically. An elaboration of this association on a histological level is needed. In human triploid fetuses severe mandibular retrognathia and deviations in the cranial base have previously been described radiographically (without cephalometry) and cervical column fusions radiographically as well as histologically. Therefore, triploid fetuses were chosen to elucidate the cranial base cephalomterically and histologically. In the present study, eight triploid fetuses were analyzed radiographically and histologically focusing especially on the cranial base, which borders to the spine and to which the jaws are attached. A histological analysis of the cranial base has not previously been performed in triploid cases. An enlarged cranial base angle and a retrognathic position of the mandible were documented cephalometrically on radiographs of all cases. Histologically, malformations were observed in the cranial base as well as in the spine. These are new findings indicating the association between the occipital bone and the uppermost vertebra in the body axis. As the notochord connects the cervical column and the cranial base in early prenatal life, molecular signaling from the notochord may in future studies support the notochord as the developmental link between abnormal development in the spine and the cranial base.