| Abstrakt: |
Objectives: Understanding organ morphogenesis gives insights into the mechanisms of congenital anomalies development. The magnetic resonance imaging is a powerful tool for the morphological assessment of the brain in embryos and fetuses. This paper is an observational descriptive study of morphological research concerning the developing brain in the first trimester of pregnancy using a correlative anatomical and micro-MRI analysis. The aim of this is study is to depict structures within the embryonic and early fetal brain, which have not been previously documented in literature by micro-MRI. Methods: We examined in vitro 12 human embryos ranging from 6 and 10 gestational weeks and 8 fetuses between 11 and 14 gestational weeks. Micro-MRI investigation was performed with a Bruker BioSpec 70/16USR scanner (Bruker BioSpin MRI GmbH, Ettlingen, Germany) operating at 7.04 Tesla. Protocols based on both T1 and T2 evolutions were employed. Besides the 2D axial scanning with 300 microns slice thickness and different inter-slice distances, scans for 3D reconstruction were also performed. Results: We describe the morphological characteristics of the developing brain in the first trimester of pregnancy. We also present the acquisition parameters which were modified for each embryo in order to obtain an increased spatial resolution, which makes possible the acquisition of high quality micro-MR images. Accurate details of the embryonic brain are reported. At 9 gestational weeks the lateral and medial ganglionic eminences and the laminar structure of the ventral wall of the cerebral hemispheres were identified. The internal capsule and nucleus accumbens were documented at 10 gestational weeks. The hippocampus, subthalamic nucleus, red nucleus, inferior olivary nuclei, substantia nigra, putamen, globus pallidus and claustrum were firstly seen at 12 gestational weeks. The medial and lateral portions of the globus pallidus, the nuclei gracilis and cuneatus as well as the head of the caudate nucleus were well depicted at 14 gestational weeks. Conclusions: Studies of embryology are still needed for a complete assessment of the developing brain. Micro-MRI offers to embryologists an alternative to the classical histological techniques. By micro-MRI we identified some nervous structures such as nucleus accumbens, subthalamic nucleus, red nucleus, internal capsule, inferior olivary nucleus which have not been previously documented by this method in the first trimester of pregnancy. Other nervous structures such as the lentiform nucleus, epiphysis, claustrum, anterior comissure, habenular comissure, as well as the laminar structure of the subpallium were depicted by micro-MRI at earlier gestational ages as previously reported in literature. Micro-MRI is feasible for the morphological studies of embryos, providing accurate images due to the high spatial resolution. It is also reproducible and doesn't affect the integrity of the specimens which can be submitted to further studies. [ABSTRACT FROM AUTHOR] |
