3D-reconstruction of craniofacial structures of a human anencephalic fetus. Case report

Morphometric characteristics of anencephalic skulls - A comparative study

Anencephaly is the most severe form of a neural tube defect resulting from the incomplete occlusion of the anterior neuropore in the fourth week of development and associated with a severely underdeveloped brain mass. As desmal ossification of the neurocranium is induced by the presence of soft tissues (brain), no bone develops as direct consequence of the missing brain. The cranial base, by contrast, is formed by chondral ossification, which is genetically determined, and thus present also in anencephaly. Morphometric characteristics of anencephalic skulls, however, have not yet been investigated in sufficient detail before. In this study we therefore comparatively assessed macroscopic morphological-anatomical and cephalometric CT data on structures and dimensions of 11 macerated anencephalic and 4 normal neonatal skulls highlighting skeletal morphological differences. The most striking results were the missing skullcap and the greatly changed morphology of the existing skull bones, which were reduced in size. The parameters of the skull base, the transverse orbital diameter and maxillary width were significantly smaller in anencephalic skulls. The morphology of the viscerocranium appeared similar to that of normal neonatal skulls. The results of this study can be used in diagnosis and skeletal classification for anencephaly. This can help identify bones that are incomplete, fragmented and taphonomically altered, which is often the case in historical and forensic studies.

Morphometric Evaluation of Craniofacial and Alveolar Arch Structures in Anencephalic Human Fetuses: A Cadaveric Study

Objective

The aim of the present study was to compare the morphometrics of the craniofacial and alveolar arch structures of anencephalic fetuses with those of normal human fetuses without anencephaly or any other anomaly.

Design

Original article.

Methods

Standard lateral and posteroanterior cephalometric radiographs of 23 anencephalic and 33 normal human fetuses aged between 21 and 40 weeks of gestation were compared. These fetuses were divided into three periods based on gestational age, and vertical, sagittal, transverse, and angular measurements were taken in the cranial base and facial regions. Moreover, intraoral measurements from the maxillary and mandibular arches were also made to determine the width and depth.

Results

N-S and S-Ba lengths and the N-S-Ba angle, measured on lateral cephalometric radiographs, were statistically smaller in anencephalic fetuses ( p < .05). The S-N-ANS, S-N-Pg, and ANS-N-Pg angles and the Go-Me length were significantly greater in anencephalic fetuses ( p < .05). Maxillary length, ramus length, and anterior facial heights were similar in both groups. On posteroanterior radiographs, all parameters except bigonial distance were found to be smaller in the anencephalic fetuses ( p < .05). Maxillary alveolar width was small among anencephalic fetuses in all three periods; whereas, the mandibular alveolar width was narrow only in the third period.

Conclusion

Cranial and facial structures were affected morphometrically to various degrees in anencephalic cases. The most significant alterations in anencephalic cases were related to measurements in the transverse direction. This indicated that cephalic tissue influenced not only the cranial base but also all facial structures.

Three-dimensional reconstructions from non-deparaffinized tissue sections

Three-dimensional (3-D) reconstruction from microscopic images represents a useful tool for the study of biological structures in embryology and developmental biology. However, it is usually necessary to cope with many difficulties connected with the preparation of specimens. In order to minimize mutual displacement of structures in successive sections, the applicability of non-deparaffinized tissue sections for 3-D reconstruction was tested. Chicken embryos were fixed and stained in toto with eosin and then embedded in paraffin. About 30-mum-thick non-deparaffinized serial sections were used for obtaining initial data for 3-D reconstruction of larger stacks of embryonic bodies using either fluorescence or confocal microscope. The same sections served for both collecting optical serial sections of mesonephros as source images for its 3-D reconstruction, and immunohistochemical detection of fibronectin, laminin and vimentin. It was found that sections with retained paraffin preserve the mutual spatial relationships of tissue components as well as provide an excellent differentiation of structure. It makes the process of 3-D reconstruction easier. The localization of the products of immunohistochemical reactions demonstrated the co-localization of fibronectin and laminin in basal laminas and the presence of vimentin in glomeruli and mesenchymal tissue. The use of non-deparaffinized sections represents a less time consuming and more effective alternative to thin histological sections for the purpose of 3-D reconstruction, and enables further application of material.

Anencephaly: MRI findings and pathogenetic theories

We describe the MRI appearances of an anencephalic newborn who survived for 13 h; particularities of this case are male gender and the absence of other associated malformations. Moreover, we discuss the pathogenetic theories of anencephaly, correlating MRI findings with embryological data. An exencephaly-anencephaly sequence due to amnion rupture is hypothesized.

3D reconstruction of the cardiovascular and central nervous system of a human embryo Carnegie-stage 15--case report

A human embryo at Carnegie stage 15 was serially sectioned and 3D computer aided reconstructions were made to demonstrate the cardiovascular system and cranial structures and to study developmental variations at this stage. The development of the heart and pharyngeal arteries was according to the existing literature. Differences were found in the development of the arterial circle of Willis and the central nervous system. The cranial venous system seemed to show great variability. Whereas the telencephalon was not developed according to the stage, the development of the hypophysis had occurred prior to stage 15. From the results we conclude that there are remarkable individual differences in embryological differentiation of structures which have to be taken into account during staging of human embryos.

Prenatal craniofacial morphogenesis: four-dimensional visualization of morphogenetic processes

OBJECTIVES

Basic research concerning craniofacial development presently runs along two pathways, namely the molecular and the morphometric. This gap needs to be bridged.

DESIGN

Using histological serial sections of human fetuses computer-aided three-dimensional reconstructions were made (Software Analysis, SIS) with special focus given to all anatomical structures of the orofacial region of the growing head.

RESULTS

All reconstructions can be viewed from any rotation and they are available for virtual dissection according to anatomical rules. As an example, the prenatal development of the human mandible with the formation of the mental foramen therein is described. Furthermore, the spatial arrangement of bone, cartilage and nerves is presented in three dimensions in different developmental stages. The interaction of tissues with possible morphogenetic interaction is discussed.

CONCLUSIONS

This work serves as a reference system for prenatal development in comparison with pathological development.