Central nervous system developmentand anatomy

Abstract

Figure 2.1 Basic three orthogonal sections of the brain. For easy understanding of brain anatomy and neuroimaging, these three sections are fundamentalProsencephalic development (2-3 months’ gestation)holoprosencephaly, agenesis of the corpus callosum, agenesis of the septum pellucidum, septo-optic dysplasiaNeuronal proliferation (3-4 months’ gestation)micrencephaly, macrencephalyNeuronal migration (3-5 months’ gestation)schizencephaly, lissencephaly, pachygyria, polymicrogyriaOrganization (5 months’ gestation to years postnatal)idiopathic mental retardationMyelination (birth to years postnatal) cerebral white matter hypoplasiaFigure 2.2 Developing brain and spinal cord during pregnancy. The fetal central nervous system changes in size and appearance from an early premature structure into a late mature structure with gyral formation. CH, cerebral hemisphere; C, cerebellum; D, diencephalon; M, medulla; SC, spinal cord; f, forebrain; mb, midbrain; IV, fourth ventricle; GA, gestational ageFigure 2.3 Serial magnetic resonance images (MRI) of early fetus (7 weeks of gestation). Upper; serial coronal MRI of the fetus at 7 weeks’ gestational age. Lower, serial sagittal MRI of the fetus at 7 weeks’ gestational age. Germinal matrix cannot be detected. Image contributed by Dr Kinoshita, from AJNR 2001;22:382 and Clinical Imagiology 2001;17:1392, with permissionFigure 2.4 Magnetic resonance sectional images and magnetic resonance surface-rendering images of a stillborn infant at 21 weeks of gestation. Note the germinal matrix (arrow) and migrating neuroblast (arrowhead). In the lower figures, the ventricular system is demonstrated in blue and the germinal matrix in orange. Image courtesy of Dr Kinoshita, from Jap J Clin Radiol 1999;44:1235, with permissionFigure 2.5 Photomicrograph of a lateral view of the brain of a stillborn fetus (20 weeks, crown-rump length 170 mm). From Moore KL, Persaud TVN and Shiota K. Color Atlas of Clinical Embryology. 2nd edn; Philadelphia: W.B. Saunders, 2000, with permission. Specimen was from Congenital Anomaly Research Center, Kyoto University Graduate School of MedicineFigure 2.6 Photomicrograph of a lateral view of the brain of a stillborn fetus (25 weeks). From Moore KL, Persaud TVN, Shiota K. Color Atlas of Clinical Embryology. 2nd edn. Philadelphia: W.B. Saunders, 2000, with permission. Specimen was from the Congenital Anomaly Research Center, Kyoto University Graduate School of MedicineFigure 2.7 Three-dimensional reconstruction magnetic resonance images (MRI) of the brain surface, germinal matrix and ventricular system. Successive MRIs of stillborn fetuses show developmental changes in the lateral configuration of the brain, germinal matrix and ventricular system. The brain surfaces (upper row), germinal matrix (middle row, orange) and ventricular system (lower row, blue) of human fetal brain were reconstructed by surface rendering. The volume of the germinal matrix increased until 23 weeks’ gestational age and decreased rapidly at 28 weeks’ gestational age. Note how the lateral ventricles change from fetal type, with vesicular aspect and bicornuate shape, to adult type with increasing gestational age. Image courtesy of Dr Kinoshita, from AJNR 2001;22:382, with permissionFigure 2.8 Serial axial magnetic resonance images (MRI) of postmortem stillborn fetuses between 15 and 28 weeks of gestation. Note the lateral ventricular change from fetal type, with vesicular aspect and bicornuate shape, to adult type. Image courtesy of Dr Kinoshita, from Clinical Imagiology 2001;17:1392, with permissionFigure 2.9 Serial coronal magnetic resonance images of stillborn fetuses between 15 and 28 weeks of gestation. Note the lateral ventricularchange from fetal type, with vesicular aspect and bicornuate shape, to adult type. Image courtesy of Dr Kinoshita, from Clinical Imagiology 2001;17:1392, with permissionFigure 2.10 Basic anatomical structure of sagittal cutting section of the brain. CC, corpus callosumFigure 2.11 Basic anatomical structure of coronal cutting section of the brainFigure 2.12 Basic anatomical structure of the ventricular system of the brain.