Neural System - Fetal: Difference between revisions

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{{Neural Links}} | [[Neural Crest Development]] | [[Sensory System Development]]  
{{Neural Links}} | [[Neural Crest Development]] | [[Sensory System Development]] | [[Second Trimester]] | [[Third Trimester]] | [[:Category:Fetus|Category:Fetus]]


==Some Recent Findings==
==Some Recent Findings==

Revision as of 09:59, 30 January 2014

Embryology - 28 Mar 2024    Facebook link Pinterest link Twitter link  Expand to Translate  
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Introduction

During the fetal period there is ongoing growth in size, weight and surface area of the brain and spinal cord. Microscopically there is ongoing: cell migration, extension of processes, cell death and glial cell development.

Cortical maturation (sulcation and gyration) and vascularization of the lateral surface of the brain starts with the insular cortex (insula, insulary cortex or insular lobe) region during the fetal period. This cerebral cortex region in the adult brain lies deep within the lateral sulcus between the temporal lobe and the parietal lobe.

This long development time generates the most complex structure within the embryo and the long time period of development means in utero insult during pregnancy may have consequences to development of the nervous system.


Neural Links: ectoderm | neural | neural crest | ventricular | sensory | Stage 22 | gliogenesis | neural fetal | Medicine Lecture - Neural | Lecture - Ectoderm | Lecture - Neural Crest | Lab - Early Neural | neural abnormalities | folic acid | iodine deficiency | Fetal Alcohol Syndrome | neural postnatal | neural examination | Histology | Historic Neural | Category:Neural

| Neural Crest Development | Sensory System Development | Second Trimester | Third Trimester | Category:Fetus

Some Recent Findings

  • Local tissue growth patterns underlying normal fetal human brain gyrification quantified in utero[1] "We applied recent advances in fetal MRI motion correction and computational image analysis techniques to 40 normal fetal human brains covering a period of primary sulcal formation (20-28 gestational weeks). ...We detected increased local relative growth rates in the formation of the precentral and postcentral gyri, right superior temporal gyrus, and opercula, which differentiated between the constant growth rate in underlying cerebral mantle and the accelerating rate in the cortical plate undergoing folding. Analysis focused on the cortical plate revealed greater volume increases in parietal and occipital regions compared to the frontal lobe. Cortical plate growth patterns constrained to narrower age ranges showed that gyrification, reflected by greater growth rates, was more pronounced after 24 gestational weeks. Local hemispheric volume asymmetry was located in the posterior peri-Sylvian area associated with structural lateralization in the mature brain. These maps of fetal brain growth patterns construct a spatially specific baseline of developmental biomarkers with which to correlate abnormal development in the human."
  • Development of fetal brain sulci and gyri: assessment through two and three-dimensional ultrasound and magnetic resonance imaging[2]

Human Neural Timeline

Timeline of events in Human Neural Development

Timeline of events in Normal Human Neural Development[3]

Fetal - Second Trimester

Brain ventricles and ganglia development 03.jpg Brain fissure development 02.jpg
Brain and Ventricular Development[4] Brain Fissure Development[4]


Human brain at three months (median sagittal section) Human brain at four months (inferior surface) Human brain at five months (outer surface)
Three months (median sagittal section) Four months (inferior surface) Five months (outer surface)

Fetal - Third Trimester

Three-dimensional magnetic resonance imaging and image-processing algorithms have been used to quantitate between 29-41 weeks volumes of: total brain, cerebral gray matter, unmyelinated white matter, myelinated, and cerebrospinal fluid (grey matter- mainly neuronal cell bodies; white matter- mainly neural processes and glia). A study of 78 premature and mature newborns showed that total brain tissue volume increased linearly over this period at a rate of 22 ml/week. Total grey matter also showed a linear increase in relative intracranial volume of approximately 1.4% or 15 ml/week. The rapid increase in total grey matter is mainly due to a fourfold increase in cortical grey matter. Quantification of extracerebral and intraventricular CSF was found to change only minimally.[5]

Thyroid System and Neural Development

Human thyroid system and neural development.jpg

Timeline of human thyroid system and brain development from conception to birth.[6] (Estimation of neurogenesis adapted from Bayer et al.[7])

Links: Endocrine - Thyroid Development

Sulcation and Gyration

Cortical maturation (sulcation and gyration) and vascularization of the lateral surface of the brain starts with the insular cortex (insula, insulary cortex or insular lobe) region during the fetal period. This cerebral cortex region in the adult brain lies deep within the lateral sulcus between the temporal lobe and the parietal lobe.

  • sulcation - The process of brain growth in the second to third trimester which forms sulci, grooves or folds visible on fetal brain surface as gyri grow (gyration). Abnormalities of these processes can lead to a smooth brain (lissencephaly).
  • gyration - The development of surface folds on the brain (singular, gyrus)

Insular Gyral and Sulcal Development

  • 13-17 gestational weeks - appearance of the first sulcus
  • 18-19 gestational weeks - development of the periinsular sulci
  • 20-22 gestational weeks - central sulci and opercularization of the insula
  • 24-26 gestational weeks - covering of the posterior insula
  • 27-28 gestational weeks - closure of the laeteral sulcus (Sylvian fissure or lateral fissure)

(Data from: Afif A, etal., 2007)

Three-dimensional magnetic resonance imaging and image-processing algorithms have been used to quantitate between 29-41 weeks volumes of: total brain, cerebral gray matter, unmyelinated white matter, myelinated, and cerebrospinal fluid (grey matter- mainly neuronal cell bodies; white matter- mainly neural processes and glia). A study of 78 premature and mature newborns showed that total brain tissue volume increased linearly over this period at a rate of 22 ml/week. Total grey matter also showed a linear increase in relative intracranial volume of approximately 1.4% or 15 ml/week. The rapid increase in total grey matter is mainly due to a fourfold increase in cortical grey matter. Quantification of extracerebral and intraventricular CSF was found to change only minimally.

(Text - modified from Huppi etal., (1998) Quantitative magnetic resonance imaging of brain development in premature and mature newborns. Ann Neurol 43(2):224-235.)


Neural development will continue after birth with substantial growth, death and reorganization occuring during the postnatal period.


Links: Neuroscience - Regional specification of the developing brain

References

  1. <pubmed>21414909</pubmed>| PMC3093305
  2. <pubmed>20878170</pubmed>
  3. Report of the Workshop on Acute Perinatal Asphyxia in Term Infants, U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health, National Institute of Child Health and Human Development, NIH Publication No. 96-3823, March 1996.
  4. 4.0 4.1 <pubmed>19339620</pubmed>| PMC2721010 | J Neurosci.
  5. <pubmed>9485064</pubmed>
  6. <pubmed>12060827</pubmed>
  7. <pubmed>8361683</pubmed>

Journals

Online Textbooks

Developmental Biology (6th ed) Gilbert, Scott F. Sunderland (MA): Sinauer Associates, Inc.; c2000. Formation of the Neural Tube | Differentiation of the Neural Tube | Tissue Architecture of the Central Nervous System | Neuronal Types | Snapshot Summary: Central Nervous System and Epidermis

Neuroscience Purves, Dale; Augustine, George J.; Fitzpatrick, David; Katz, Lawrence C.; LaMantia, Anthony-Samuel; McNamara, James O.; Williams, S. Mark. Sunderland (MA): Sinauer Associates, Inc. ; c2001 Early Brain Development | Construction of Neural Circuits | Modification of Brain Circuits as a Result of Experience

Molecular Biology of the Cell (4th Edn) Alberts, Bruce; Johnson, Alexander; Lewis, Julian; Raff, Martin; Roberts, Keith; Walter, Peter. New York: Garland Publishing; 2002. Neural Development | The three phases of neural development

Health Services/Technology Assessment Text (HSTAT) Bethesda (MD): National Library of Medicine (US), 2003 Oct. Developmental Disorders Associated with Failure to Thrive

Search NLM Online Textbooks- "neural development" : Developmental Biology | The Cell- A molecular Approach | Molecular Biology of the Cell | Endocrinology

Reviews

<pubmed>16314867</pubmed> <pubmed>19206138</pubmed>

Articles

<pubmed>18230116</pubmed>

Search PubMed

Search Pubmed: Fetal Brain Development | Fetal Spinal Cord Development | Fetal Neural Development


Glossary Links

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Cite this page: Hill, M.A. (2024, March 28) Embryology Neural System - Fetal. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Neural_System_-_Fetal

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G