Biomedical subjects

I Kjaer

Publications and source records attributed to I Kjaer.

At least 19 recordsLinked to original sources

PubMed2003

A histological and radiological investigation of the nasal bone in fetuses with Down syndrome.

OBJECTIVES: Previous studies of nasal bone development in Down syndrome have used radiographs or ultrasound for the detection of nasal bone length or nasal bone absence. The aim of this study was to investigate the presence and size of the nasal bones in postmortem Down syndrome fetuses by means of radiographs and histological examination. METHODS: Thirty-three aborted human fetuses (gestational age 14-25 weeks) with Down syndrome were included. A mid-sagittal tissue block was excised from the skull base to the foramen magnum and along the lateral aspect of the spine. Radiographs of the tissue block were taken in lateral, frontal and axial projections. The length of the nasal bone was measured. The tissue blocks were cut in serial sections and stained. The crown-rump length (CRL), foot length (FL) and number of ossified bones in the hand and foot (CNO) were recorded. RESULTS: A total of 8/33 fetuses had bilateral nasal bone absence and two had unilateral absence. In fetuses with radiographically diagnosed nasal bone absence, no nasal bone could be found histologically. The majority of the Down syndrome fetuses had CRL, FL and CNO values within the range of those for normal age-matched fetuses. Nasal bone length was normal or reduced. CONCLUSIONS: Absence of the nasal bone was registered by postmortem examination in one-third of fetuses with Down syndrome. In some fetuses this could be a result of delayed maturation associated with Down syndrome. The phenotypic differences in nasal bone appearance may reflect genotypic differences in the Down syndrome group.

Autopsy↗

PubMed2003

The pre-natal development and osseous growth of the human cerebellar field.

OBJECTIVES: To describe the pre-natal development of the bones that enclose the cerebellum and part of the brain stem (the neuro-osteological cerebellar field) in the mid-sagittal plane. DESIGN: Radiographic, cephalometric and histologic examination of normal pre-natal human fetuses; 50 normal fetuses, with crown-rump length of 18-227 mm and approximate gestational age from 6 to 26 weeks. RESULTS: The cerebellar field expressed extensive growth during development both sagittally and vertically. Because of changes in shape, the field was displaced in an anterio-caudal direction. CONCLUSION: In the present study we recorded normal measurements of size, shape and position of the cerebellar field. These standards can be used as references in skeletal analysis of cases with cranial abnormalities and cerebellar malformations.

Cephalometry↗

PubMed2002

Spatiotemporal expression of NGFR during pre-natal human tooth development.

OBJECTIVES: The relation between nerve growth factor receptor (NGFR) in the human pre-natal tooth buds and the dental follicle was investigated. In particular, we sought to determine if there is a specific pattern of p75NGFR expression in developing human tooth buds and their surrounding tissue. SETTING AND SAMPLE POPULATION: The Department of Orthodontics at Copenhagen University, Denmark. Histological sections from 11 fetuses, aged 11-21 gestational weeks. METHOD: The sections were studied by conventional immunohistochemistry. RESULTS: Specific spatiotemporal patterns of p75NGFR reactions were observed in the tooth buds and dental follicle: Before matrix production by the ameloblasts, the entire inner enamel epithelium and the entire dental follicle display p75NGFR immunoreactivity; after matrix production is initiated, the immunoreactivity of the matrix producing cells is lost, as is that of the dental follicle adjacent to these matrix-producing cells. CONCLUSION: A unique spatiotemporal distribution of NGFR in the pre-eruptive human tooth bud was demonstrated.

Dental Sac↗

PubMed2002

Segmental odontomaxillary dysplasia: clinical, radiological and histological aspects of four cases.

Segmental odontomaxillary dysplasia (SOD) is a rare developmental disorder of the maxilla, primarily involving the posterior part of the maxilla. Clinically, the disorder is often diagnosed in early childhood due to a unilateral buccolingual expansion of the posterior alveolar process, gingival enlargement, absence of one or both premolars in the affected region, delayed eruption of the adjacent teeth and malformations of the primary molars. In this report, four patients with SOD are described. The findings were similar to earlier reports, but for the first time an ipsilateral rough erythema on the skin in two of the subjects is reported.

Alveolar Process↗

PubMed2002

Biological interpretation of the correlation of emergence times of permanent teeth.

The eruption mechanism is not fully understood. It is known that the dental follicle is essential and that experimentally provoked denervation influence the process of eruption. Accordingly, the purpose of this study was to elucidate the eruption pattern in a human population and relate this pattern to the pattern of jaw innervation. The eruption pattern was evaluated from the correlation between the emergence times of different teeth in the permanent dentition based on longitudinal data from a large national registry (12,642 boys and 12,095 girls). Correlations coefficients were generally high (>0.5) and higher between teeth within the same tooth groups (i.e. incisors, canines and premolars, and molars) than between teeth from different tooth groups. It was shown that the correlation in emergence of teeth closely followed the pattern of innervation of the jaws. Thus the study supported the hypothesis concerning a possible association between eruption and innervation.

Adolescent↗

PubMed2001

Cranial and hand skeleton in fragile X syndrome.

The purpose of the present study was to track prenatally observed skeletal deviations in radiographs from fragile X syndrome children and young adults in a search for improvement of early diagnostics of fragile X syndrome. The material consisted of craniofacial profile radiographs and hand radiographs from six males age between 2 years 9 months and 20 years 3 months. Craniofacial radiographs showed normal morphology of the nasal bone in all cases. In five cases the sella turcica could be analyzed. In two cases the anterior wall of the sella was oblique, and in two cases the dorsum sellae appeared short. In one case the sella turcica had normal structure. In two cases, the cervical column was suitable for examination. In one, body fusion and short arcus occurred. Of the six hand radiographs analyzed, the hand skeleton appeared normal in the youngest male. In the other five cases there was a deviant location of the carpal bones in the developmental field corresponding to the first finger. Skeletal maturity was delayed in all cases. In conclusion, the prenatally registered morphological deviations in the skeletal development of fragile X syndrome fetuses were found in 5 of 6 fragile X males and young adults. We suggest that a skeletal analysis be considered in the phenotypic classification of children with fragile X syndrome.

Adolescent↗

PubMed2001

Bi-iliac distance and iliac bone position compared to the vertebral column in normal fetal development.

Prenatal standards of bi-iliac width were not found in the literature based on autopsy investigations, nor was the caudo-cranial position of the ilia compared to the vertebral column. The first purpose of the present study was to establish normal standard values for the bi-iliac distance in fetal life, the second to evaluate the level of the iliac bones proportional to the ossified vertebral column. Whole body radiographs in antero-posterior projections from 98 human fetuses (36 female and 44 male fetuses, as well as 18 fetuses on which the sex had not been determined) were analyzed in the study. The fetuses derived from spontaneous or induced abortions and they were radiographed as part of the required autopsy procedure. The crown-rump-length (CRL) of the fetuses varied from 32 to 245 mm. The outer and inner bi-iliac distance was measured from the radiographs with a digital Helios slide caliper. The caudo-cranial position of the iliac bones was evaluated. The present study shows that in normal fetal development there is a continuous linear enlargement of the pelvic region in the transverse and vertical planes. The upper iliac contour stays at the level of the first sacral vertebral body, whereas the lower iliac line moves caudally. Significant differences between male and female fetuses were not found. The value of the present study is that the results can be used as reference standards in prenatal pathology.

Embryonic and Fetal Development↗

PubMed2001

Prenatal localization of the dorsal root ganglion in different segments of the normal human vertebral column.

STUDY DESIGN: Vertebral columns from 11 normal human fetuses (10-24 weeks of gestation) derived from spontaneous abortions were examined as part of the legal autopsy procedure including spinal cord analysis. OBJECTIVES: To study the localization of the dorsal root ganglion in the normal fetal spine and to relate the dorsal root ganglion location to the ossification of the vertebral bodies and vertebral arches. SUMMARY OF BACKGROUND DATA: The normal and pathologic ossification pattern of the fetal human spine has been studied. There has been no study addressing the localization of the dorsal root ganglion in normal and pathologic axial development. METHODS: The dorsal root ganglion were studied by using histology (horizontal sections) and morphometric measurement. RESULTS: The study showed: 1) The dorsal root ganglion appeared before ossification of the spine; 2) The dorsal root ganglion had an oval shape in all cases; 3) The longitudinal axis of dorsal root ganglion was directed anterolaterally in the cervical and lumbosacral segments and mainly laterally in the thoracic segment; 4) During development, the dorsal root ganglion changed position according to the body axis; and 5) The para-axial ossification protected the dorsal root ganglion differently in the different axial segments. CONCLUSIONS: The dorsal root ganglion appeared before ossification. The distance from the dorsal root ganglion to the body axis increased during development. In the different segments of the spine, different orientations and different locations of the dorsal root ganglion were observed in relation to osseous spine components. The results can be used as reference data for future studies on the dorsal root ganglion in pathologic spines.

Ganglia, Spinal↗

PubMed2001

Eruption of the central incisor, the intermaxillary suture, and maxillary growth in patients with a single median maxillary central incisor.

The occurrence of a single median maxillary central incisor (SMMCI) is a very rare condition and might be a sign of a more severe midline defect, which could be a mild degree of holoprosencephaly. Absence of the internasal and partial absence of the intermaxillary suture has been observed in a fetus with holoprosencephaly. The purpose of this study was to evaluate the intermaxillary suture, the eruption pattern of the single central incisor in the SMMCI condition, and the growth of the maxilla in a group of patients with SMMCI. A similar study was not found in the scientific literature. The material included orthopantomographs, dental radiographs, and lateral cephalometric radiographs from 11 patients with an SMMCI. The orthopantomographs and dental radiographs showed that the intermaxillary suture was abnormal anterior to the incisive foramen; however, the SMMCI erupted within the expected time interval. Superimposition on stable structures on lateral cephalometric radiographs from two untreated patients, in which growth analysis was possible, showed that the horizontal and vertical growth of the maxilla was normal. Due to the sutural midline defect it is suggested that a transversal growth analysis is included in all treatment planning of SMMCI patients.

Adolescent↗

PubMed2001

Face, palate, and craniofacial morphology in patients with a solitary median maxillary central incisor.

The occurrence of a solitary median maxillary central incisor (SMMCI) is a very rare condition and might be a sign of a mild degree of holoprosencephaly. In this investigation, material from 10 patients, nine girls and one boy with a SMMCI (8-17 years of age) registered in orthodontic clinics was examined. The purpose was to evaluate the clinical characteristics and craniofacial morphology in this group of patients. Oral photographs, study casts, profile radiographs, and orthopantomograms were analysed. The study showed that this group of SMMCI patients were characterized by an indistinct philtrum, an arch-shaped upper lip, absence of the fraenulum of the upper lip, a complete or incomplete mid-palatal ridge, a SMMCI, and nasal obstruction or septum deviation. The craniofacial morphology of the nine girls, compared with normal standards for girls showed a short anterior cranial base, a short, retrognathic and posteriorly inclined maxilla, and a retrognathic and posteriorly inclined mandible. Furthermore, the sella turcica had a deviant morphology in five of the 10 subjects. The results indicate that the presence of a SMMCI should not be considered as a simple dental anomaly, since it may be associated with other clinical characteristics and more complex craniofacial malformations. It is therefore suggested that the SMMCI condition in future studies is classified according to clinical symptoms and craniofacial morphology.

Adolescent↗

PubMed2001

Histological investigation of the palatine bone in prenatal trisomy 21.

OBJECTIVE: The purpose of the present study was to investigate the horizontal part of the palatine bone in palates from human fetuses with trisomy 21 to improve the phenotypic classification of the genotypic anomaly. METHODS: Material from 23 human trisomy 21 fetuses was included in the study. The crown rump lengths of the fetuses ranged from 80 mm to 190 mm, corresponding to about 12 to 21 weeks of gestational age. The material was examined histologically. RESULTS AND CONCLUSIONS: Histological examination demonstrated four different palatal phenotypes on the basis of the development of the horizontal part of the palatine bone: type I, palatine bone complete; type II, the mesial region of the horizontal part of the palatine bone is lacking; type III, complete absence of the horizontal part of the palatine bone; and type IV, auxiliary bones in the region of the transpalatine suture. This finding shows that different types of malformations may occur in the horizontal part of the palatine bone in human trisomy 21 fetuses.

Cartilage↗

PubMed2001

Craniofacial morphology, dentition, and skeletal maturity in four siblings with Seckel syndrome.

OBJECTIVE: To describe the craniofacial morphology, dentition, and hand maturity in four siblings with Seckel syndrome. PATIENTS: Two boys and two girls, with Seckel syndrome. The children studied showed extreme growth retardation, severe microcephaly, bird-headed profile with receding chin, prominent nose, mental retardation, and extremely delayed skeletal maturation. The growth hormone axis and pituitary thyroid function was normal. METHODS: Skeletal and dental development were investigated from radiographic material, and a cephalometric analysis was performed from profile radiographs. RESULTS: The craniums were remarkably small with an extremely short anterior cranial base (-4.3 to -5.5 standard units) and maxillary length (-3.8 to -4.7 SU). Differences in the morphology of the sella turcica were observed in girls and boys. Tooth maturity progressed normally. Tooth agenesis and tooth malformations were observed. Taurodontic root morphology was observed only in the girls. The approximate skeletal maturity showed retardation from 4 years 3 months to 4 years 11 months. Malformations of the hand-wrist skeleton occurred in the epiphyseal ossification centers of the middle phalangeal bone in the second, third, and fourth finger and in the distal phalangeal bone in the fifth finger. The epiphyseal ossification centers were lacking in the middle and distal phalangeal bones of the fifth finger. CONCLUSION: The underlying gene defect in the affected children seemingly affects bone development and growth but not dental maturation and eruption.

Adolescent↗

PubMed2001

Craniofacial tissues including tooth buds in fetal hypohidrotic ectodermal dysplasia.

OBJECTIVE: Hypohidrotic ectodermal dysplasia (HED) comprises defects in hair, teeth, and sweat glands. Disturbances in other ectodermal tissues have been associated with the condition. Our objective was to examine ectodermal craniofacial structures histologically in a fetus with HED and to compare the findings to similar structures in normal control fetuses. MATERIALS AND METHODS: A male fetus diagnosed with HED was therapeutically aborted in the 15th week of gestation. One male and two female healthy fetuses were used as normal controls. All fetuses were examined with parental consent, and had comparable sizes. Their bone maturation stage in the hand was identical. Tissue blocks from the craniofacial region were excised from all fetuses and prepared for histological analysis (formalin fixed, stained with toluidine blue or Alcian blue). The tissues examined were: tooth buds, skin and skin appendages, oral mucosa including minor salivary glands, major salivary glands, lacrimal glands, and adenohypophysis. RESULTS: Fewer tooth buds, minor salivary glands, and hair follicles were observed in the HED fetus as compared to controls. The structures of the epidermal components in the developing HED organs were loose and disorganised. The adhesion between the ectodermal and mesenchymal organ components in the HED fetus seemed to be disturbed.

Ectodermal Dysplasia↗

PubMed2000

Aspects of skeletal development in fragile X syndrome fetuses.

The purpose of the present investigation was to describe the skeletal development in prenatal fragile X syndrome. We studied fetuses (4 males, 2 females), with gestational ages (GA) 12-14 weeks, from 5 unrelated, different, known carrier mothers. Because of trauma to the fetus during abortion, different parts of the 6 fetuses were available for investigation. The vertebral column and the facial skeleton of all the fetuses were examined, the feet and hands of 5 fetuses, and the cranial base of 3 fetuses. The tissue remnants were examined radiographically and histochemically, and the results compared with previously published normal findings. Radiographic findings included normal ossification sequence, except for 1 fetus where there was an abnormal sequence in the first finger; normal morphology of ossification centres; and nasal bones were absent in the 5 fetuses and present in 1 (14 weeks of gestation). The histological study suggests presence of an acid mucopolysaccharide malfunction in the supporting tissue, because the normal cartilage resorption and orthochromatic cartilage reactions do not appear during the initial enchondral ossification. In addition, the apoptosis of ectodermally derived cells (notochord and palatal epithelial layers) appears delayed or abnormal. The sella turcica was malformed in the 2 fetuses investigated for sella turcica morphology.

Abortion, Induced↗

PubMed2000

Abnormal timing in the prenatal ossification of vertebral column and hand in Crouzon syndrome.

We report on a radiographically examined fetus (gestational age 13 weeks) with Crouzon syndrome caused by a mutation in the gene encoding the fibroblast growth factor 2 (FGFR2). We found an approximately 2-week delay in vertebral body and hand ossification with normal vertebral arch ossification, suggesting that regionally delayed skeletal maturation might be a manifestation of FGFR2 mutation syndromes. The findings support other studies indicating that different signaling pathways control skeletal maturation in vertebral bodies and vertebral arches.

Abnormalities, Multiple↗

PubMed2000

The prenatal pituitary gland--hidden and forgotten.

The sella turcica and pituitary gland in a human fetus (18 weeks gestation) with unilateral oro-ocular cleft combined with unilateral cleft lip and palate are described histologically. In this fetus the sella turcica was not a normal sella but a caudally open funnel. The adenopituitary gland tissue was positioned ectopically within the funnel canal and in the pharyngeal submucosa.

Abnormalities, Multiple↗

PubMed2000

Prenatal malformed lumbar vertebral corpora in trisomies 21, 18, and 13, evaluated radiographically and histologically.

The aim of the present study was to compare, both radiographically and histologically, malformed vertebral lumbar corpora in trisomies 21, 18 and 13 with earlier reported normal corporal development in the axial lumbar region. Axial skeletons of human fetuses (GA 15-22 wk) derived from therapeutically induced abortion were investigated in connection with requested autopsy. The number of lumbar vertebral corpora examined for each genotype was as follows: 20 from trisomy 21, 10 from trisomy 18, and 10 from trisomy 13. After radiography in frontal, lateral and axial projections, the individual vertebral corpora were decalcified and horizontally embedded in paraffin. The blocks were serially sectioned and stained with toluidine blue and alcian blue/van Gieson. The radiographic characteristics of the vertebral corpora varied from an almost normal appearance of the corporal bone to complete clefting of the bony corpora. Histological examination showed accumulations of cartilage centrally, in some cases associated with amorphous material. Pronounced metachromatic differences were observed in the cartilaginous ground substance. The study showed identical phenotypic characteristics in the corpora from trisomy 21, trisomy 18, and trisomy 13. It is characteristic of all three genotypes that there are central anomalies, corresponding to the location of the notochord in normal corpora, and marked regional differences in metachromasia in the ground substance of the cartilage.

Abortion, Induced↗

PubMed2000

A sella turcica bridge in subjects with severe craniofacial deviations.

In earlier studies, a sella turcica bridge was stated to occur in 1.75 to 6 per cent of the population. The occurrence of a sella turcica bridge has not previously been studied in a group of patients with craniofacial deviations treated by surgery. Profile radiographs from 177 individuals who had undergone combined orthodontic and surgical treatment at the Copenhagen School of Dentistry were studied. A sella turcica bridge was registered in those subjects where the radiograph revealed a continuous band of bony tissue from the anterior cranial fossa to the posterior cranial fossa across the sella turcica. Two types of sella turcica bridge were identified. A sella turcica bridge occurred in 18.6 per cent of the subjects.

Calcinosis↗