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Biomedical subjects

G H Sperber

Publications and source records attributed to G H Sperber.

At least 19 recordsLinked to original sources
PubMed1992

Current concepts in embryonic craniofacial development.

Embryology mirrors phylogeny. The phenotypic expression of the genome is the result of differential gene transcription, the critically timed turning on and off of specific genes by transcription factors to produce cyto-, histo-, and morpho-differentiation that fleetingly reflects evolutionary stages of development during ontogeny. Hox genes regulate transcription of other structural genes and are responsible for patterning of the facial primordia. Cephalic development involves extremely complex morphogenetic mechanisms built on conserved elements that have undergone enormous evolutionary changes. Transient expression of phylogenetic origins characterize ontogeny and are reflected in defective development that may be due to inappropriate expression of Hox genes or distorted or disrupted epignetic processes. The mechanisms by which genetic information is transformed into morphological patterning by the actions of growth factors, morphogenes, and receptors are currently being identified. Biochemical, immunological, and allometric analyses of embryos and fetuses in experimental and descriptive studies are elucidating details of units of craniofacial morphogenesis--faciogenesis, palatogenesis, gnathogenesis, odontogenesis. Three-dimensional model computer-assisted reconstruction of sectioned embryos and fetuses provides a further technique for understanding the complex configurations of tissue migratory patterns and growth sites that account for normal and abnormal craniofaciogenesis.

Animals↗
PubMed1992

The aetiopathogenesis of craniofacial anomalies.

Craniofacial embryogenesis with emphasis on the mechanisms of morphogenesis as a basis for understanding developmental anomalies is reviewed. A classification of maldevelopment into malformation, deformation and disruption is illustrated by examples. A brief review of the clinical consequences of craniofacial anomalies and possible therapeutic modalities is undertaken.

Embryonic and Fetal Development↗
PubMed1991

Fiducial points for three-dimensional computer-assisted reconstruction of serial light microscopic sections of umbilical cord.

Fascicles of human sural (peripheral sensory) nerve were used as external fiducial points (FP) for accurate registration of serial light microscopic sections in three-dimensional reconstruction of human umbilical cord. This paper describes a method for embedding the FPs within the paraffin wax block simultaneously with the specimen to be sectioned. Using a new design of embedding box, the FPs are embedded close to the specimen and are transferred to the slides as part of the tissue sections. Three to four FPs were used to align and scale the serial tissue sections for digitization and computerized reconstruction, using a commercially available software program on IBM-compatible 80386 hardware. A three-dimensional solid surface graphic model of a segment of human umbilical cord was generated.

Histological Techniques↗
PubMed1990

Traumatic exodontia.

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History, 19th Century↗
PubMed1990

Floor of the median orbit in human cyclopia: an anatomical study in three dimensions.

A three dimensional study has been undertaken of the floor of the median orbit in human cyclopia. The cyclopic material consists of a full term desiccated head, a dried fetal skull and four sectioned fetal heads. Most elements in the floor of the median orbit are normal. Such abnormalities as are present in the bony floor and the related lacrimal sac are considered to be secondary to the absence of the presphenoid and the postero-inferior part of the nasal cavity. The abnormalities seen in the medial and inferior rectus muscles are considered to be secondary to the absence of a medial orbital wall and normally defined and directed optic nerves and eyeballs.

Eye Abnormalities↗
PubMed1989

Microscopic study of holoprosencephalic facial anomalies in trisomy 13 fetuses.

The cerebral and facial anatomy of four trisomy 13 fetuses was studied in order to delineate the varying degrees of expression of severity of holoprosencephaly. Fetal heads were serially sectioned and analyzed microscopically in the horizontal plane. Examples of cyclopia, cebocephaly, and a proposed new category, premaxillary dysgenesis, were studied. The last category represents the least severe end of the facial spectrum of holoprosencephaly in this series. In this condition, there are deficiencies or clefts within the premaxilla, in contrast to the usual site of clefting between the maxilla and the premaxilla. There is asymmetry of the defects in the anterior midface of all four cases.

Abnormalities, Multiple↗
PubMed1989

Anatomic findings in dicephalic conjoined twins: implications for morphogenesis.

The morphogenesis of conjoined twins is incompletely understood. We therefore conducted a postmortem study of dicephalus dibrachii dipus conjoined twins. The twins were born without pertinent history or prenatal diagnosis at 38 weeks and lived for several hours. External genitalia were female and partly duplicated; a caudal appendage was present in the thoracolumbar region. The heart and liver were shared and exhibited major abnormalities in configuration. Four lungs, three kidneys and adrenal glands, and two spleens were identified; biliary and upper gastrointestinal tracts appeared as mirror images. From these findings, we postulate three major sets of consequences arising from the anatomical disposition of the twin notochords ("paleoaxes"). 1) The degree of convergence/divergence of craniocaudal paleoaxes is variable. Convergences are maximal in the upper thoracic and sacral regions, where duplication of organs in minimal because of interaction aplasia. 2) In the horizontal plane, paleoaxes are sufficiently divergent to produce a degree of twin expression posteriorly, whereas anteriorly they converge to form a single, anterior, midline "neoaxis." Interposed between these zones of paleoaxial and neoaxial expression are areas of variable interaction aplasia. 3) The left twin was in situs solitus; the right twin was in situs inversus in a manner resembling polysplenia.

Abnormalities, Multiple↗
PubMed1987

Microscopic study of midline determinants in janiceps twins.

The earliest hitherto recorded developmental stage of human cephalothoracopagus (janiceps) twins, at 8 weeks of conceptional age, is described macroscopically and microscopically. The nearly perfect disymmetrical configuration of the 2 faces was compared with previously reported cases, and horizontal sectioning of the entire conceptus allowed detailed histologic description of the internal orientation of most organs and systems. The concept of conflicting facial and vertebral axes was explored to account for shared cerebral, facial, pharyngeal, and esophageal structures, and for aplasia of the pituitary and thymus glands and of the teeth. Critical points of changing axial orientation were identified at the mesencephalon, the Rathke pouch and third branchial arch, and with the hepato-cardio-respiratory complex split between the 2 axes. The caudal components conformed with previously reported cases.

Abdomen↗
PubMed1987

Holoprosencephalic synophthalmia (cyclopia) in an 8 week fetus.

Histopathological examination of an 8-week-old human cyclopic fetus revealed holoprosencephaly, synophthalmia, and malformed midfacial features. The telencephalon was undivided and projected a single median optic stalk partially subdivided into optic vesicles contained in a single orbit. Aberrant midfacial ossification underlay arrhinia and uncleft lips and palate. Maxillary anodontia and mandibular hypodontia prevailed. Postcranial normality was disturbed by pedal postaxial hexadactyly, suggesting trisomy 13. The exceptionally young age of the specimen distinguishes its detailed analysis from the majority of older cyclopic specimens previously reported.

Abnormalities, Multiple↗
PubMed1986

Acalvaria, holoprosencephaly, and facial dysmorphism syndrome.

An estimated 85-day-old human fetus exhibited a malformation complex consisting of holoprosencephaly, absent calvaria, exophthalmic hypertelorism, and severe bilateral midfacial orofacial clefting involving the maxillary/frontonasal prominences (oblique facial clefts), upper lip (bilateral clefts), and palate (complete cleft). This combination of dysplasias precludes assignment to previously described syndrome complexes. The presence of an olfactory nerve/ethmoidal bone complex does not conform with "classic holoprosencephaly," nor does acalvaria without cerebral dysraphism fit into the cranioschisis and exencephaly syndromes. It is postulated that this combination of anomalies is due to faulty embryogenesis of the prechordal cephalic mesenchyme, leading to failure of telencephalic cleavage and of neural crest-mediated development of the calvaria and facial prominences.

Abnormalities, Multiple↗
PubMed1985

Monozygotic twin aborted fetuses discordant for holoprosencephaly/synotia.

A pair of monozygotic twin fetuses aborted at 15 weeks were found to be discordant for holoprosencephaly and synotia. They were studied grossly, radiologically, and histologically. Features of first brancial arch dysplasia (synotia, agnathia, and astomia) and holoprosencephaly (absent ethmoid bone and Rathke's pouch) observed in one twin were contrasted with minimal dysmorphology in the co-twin. Some evidence of the twin transfusion syndrome was also apparent, perhaps contributing to the twins' spontaneous abortion.

Abnormalities, Multiple↗