Development of Cerebral Cortex in Prematurely Born Infants: Cell Proliferation, Differentiation, and Maturation of Neurons and Myelination in the Archi- and Neocortex
Increased survival of prematurely born infants is a major achievement of contemporary perinatal and neonatal medicine. However, follow-up studies have shown that many of these children exhibit impaired development including short-term morbidity and long-term physical and mental disability. Many prematurely born children, even without perinatal complications, display cognitive and educational difficulties, while the severity of these difficulties correlates with the time of birth. The development of cerebral cortex involves a highly organized, elaborate, and long-lasting series of events which are not completed by the time of birth. Indeed, many developmental events continue after the 40th postconceptual week, which explains the extended morphological, behavioral, and cognitive development of children. This chapter reviews normal cerebral cortical development and morphological evidence of cortical maturation in preterm and full-term infants. Aspects of postnatal cortical development, including cell proliferation and maturation of neurons, myelination of the temporal archi- and neocortex cortex, are discussed and compared in preterm infants and age-matched, full-term controls. A detailed overview is given of the rate of postnatal neuronal proliferation in the human dentate gyrus after premature birth as well as about the dendritic and axonal maturation of archi- and neocortical neurons. The perinatal disappearance of predominantly prenatal cell types (e.g., Cajal-Retzius cells) in preterms and the development of cortical convolutions are described. Finally, myelination of cerebral cortex in prematurely born infants is compared to full-term controls.
KeywordsGranule Cell Dentate Gyrus White Matter Lesion Hippocampal Formation Febrile Seizure
Regions of Ammon’s horn
Clusters of differentiation 31 (marker for endothelial cells)
Granule cell layer
Hilus of the dentate gyrus
Myelin basic protein
Periodic-acid Schiff reaction
Subpial granular layer
The author wishes to thank Dr Susan Totterdell (Department of Pharmacology, University of Oxford) for her critical reading and correcting the manuscript. The constructive and helpful comments on the manuscript of Dr Laszlo Seress (Central Electron Microscopic Laboratory, University of Pecs) and the excellent technical assistance of Mrs Emese Papp in the histological preparations of the tissues are gratefully acknowledged. This work was supported by the Hungarian National Science Fund (OTKA) with grant # T047109 and by the Bolyai Scholarship of the Hungarian Academy of Sciences.
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