Neural - Cerebrum Development: Difference between revisions
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* 84 days - subdivisions of the genu and splenium can be identified | * 84 days - subdivisions of the genu and splenium can be identified | ||
* 115 days - adult morphology is seen | * 115 days - adult morphology is seen | ||
Agenesis of the corpus callosum is an uncommon cerebral malformation. | |||
:Links: [http://www.ninds.nih.gov/disorders/agenesis/agenesis.htm NINDS Information] | |||
==Abnormalities== | ==Abnormalities== |
Revision as of 10:30, 22 March 2012
Introduction
The brain as it is generally recognised. The adult cerebral cortex like other neural structures has a laminar organization.
A simplified developmental sequence can be described as cell proliferation, cell migration, and finally cortical organization. In development, lamination occurs in an "inside-out" sequence earlier inside and later born neurons outside. The cortex is divided into areas which serve distinct functions including motor, sensory and cognitive processing. The lamination process requires a range of different signals including; Reelin (Reln, an extracellular protein), Disabled-1 (Dab1, an intracellular signaling molecule), and Cullin-5 (Cul5, an E3 ubiquitin ligase).
The cortex progenitor cell types are either neuron-restricted or bipotent (neuron-glial) progenitors that generate glial-restricted progenitors at mid- and late neurogenesis.
Some Recent Findings
|
Development Overview
Neuralation begins at the trilaminar embryo with formation of the notochord and somites, both of which underly the ectoderm and do not contribute to the nervous system, but are involved with patterning its initial formation. The central portion of the ectoderm then forms the neural plate that folds to form the neural tube, that will eventually form the entire central nervous system.
- Early developmental sequence: Epiblast - Ectoderm - Neural Plate - Neural groove and Neural Crest - Neural Tube and Neural Crest
Neural Tube | Primary Vesicles | Secondary Vesicles | Adult Structures |
---|---|---|---|
week 3 | week 4 | week 5 | adult |
prosencephalon (forebrain) | telencephalon | Rhinencephalon, Amygdala, hippocampus, cerebrum (cortex), hypothalamus, pituitary | Basal Ganglia, lateral ventricles | |
diencephalon | epithalamus, thalamus, Subthalamus, pineal, posterior commissure, pretectum, third ventricle | ||
mesencephalon (midbrain) | mesencephalon | tectum, Cerebral peduncle, cerebral aqueduct, pons | |
rhombencephalon (hindbrain) | metencephalon | cerebellum | |
myelencephalon | medulla oblongata, isthmus | ||
spinal cord, pyramidal decussation, central canal |
Early Brain Vesicles
Primary Vesicles
Secondary Vesicles
Late Embryonic Brain
Human embryo developing cortex (Week 8, Carnegie stage 22)
- small embryo shows approximate level of section.
- insert top right shows whole head section.
- small shaded box on whole section shows region of large image.
- layer thicknesses are shown in microns.
Early Fetal Brain
The above images are from a week 10 human fetus.
Fetal Brain
Fetal brain (3 months) | Fetal brain (4 months) | Fetal brain (5 months) |
Fissures are the major indentations, sulci (singular sulcus), that divide the brain surface into lobes and appear during fetal development as the brain grows. The images below show MRI analysis of the developing human fetal brain.
- Links: Magnetic Resonance Imaging
Developmental Overview
Cortical Neurons
Cortical layers in a historic drawing by Cajal.
Cajal-Retzius Neurons
Cajal-Retzius (CR) cells are some of the earliest generated cortical neurons arising from restricted domains of the pallial ventricular zone, and then migrate from the borders of the developing pallium to cover the cortical primordium. These early forming neurons then control the radial migration of neurons and the formation of cortical layers. In mice, this has been shown by these cells secreting the extracellular glycoprotein Reelin (Reln) and it has been suggested that these cells also fine tune multiple signaling pathways underlying the regulation of cortical regionalization.[4]
Molecular
- Fgfr1 and Fgfr2 - control excitatory cortical neuron development within the entire cerebral cortex.[6]
- Fgfr2 - proper formation of the medial prefrontal cortex (mPFC).[6]
- MARCKS - (myristoylated alanine-rich C-kinase substrate protein) a cellular substrate for PKC modulates radial glial placement and expansion.[7]
- MicroRNA - noncoding RNAs that regulate mRNA expression, highly expressed during development.[8]
- Wnt - contribute to the production of basal progenitors (non-surface dividing or intermediate progenitors).[9]
Corpus Callosum
The corpus callosum is the area of the brain which connects the two cerebral hemispheres.
- 74 days - callosal axons appear
- 84 days - subdivisions of the genu and splenium can be identified
- 115 days - adult morphology is seen
Agenesis of the corpus callosum is an uncommon cerebral malformation.
- Links: NINDS Information
Abnormalities
Hemimegalencephaly
Increased proliferation
Heterotopia
Ectopic migration
Lissencephaly
A malformations derived from abnormal neuronal migration leading to agyria (convolutions of the cerebral cortex are not fully formed) and pachygyria (convolutions of the cerebral cortex unusually thick ).
Pachygyria (Greek, pachy = "thick")
Microlissencephaly
Decreased proliferation
Polymicrogyria
Abnormal organization, numerous small gyri and a thick disorganized cortical plate lacking normal lamination, disruption of microtubule-based processes underlies a large spectrum of neuronal migration.[10]
Schizencephaly
Abnormal organization
References
- ↑ <pubmed>20108226</pubmed>
- ↑ <pubmed>19622880</pubmed>
- ↑ <pubmed>20981415</pubmed>
- ↑ 4.0 4.1 <pubmed>20668538</pubmed>| PLoS Biol.
- ↑ <pubmed>19812240</pubmed>| PMC2871377
- ↑ 6.0 6.1 <pubmed>20410112</pubmed>
- ↑ <pubmed>19666823</pubmed>
- ↑ <pubmed>19914179</pubmed>
- ↑ <pubmed>20215343</pubmed>
- ↑ <pubmed>19465910</pubmed>
Reviews
<pubmed>19732610</pubmed> <pubmed>19763105</pubmed>
Articles
<pubmed>20161753</pubmed> <pubmed>20040495</pubmed> <pubmed>20410119</pubmed> <pubmed>20410112</pubmed> <pubmed>20215343</pubmed>
Search PubMed
Search Pubmed: Cerebrum Embryology | Cerebrum Development
External Links
External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.
- Zagreb Neuroembryological Collection - contains more than 500 prenatal human brains stained with various classical neurohistological, as well as modern histochemical and immunohistochemical methods. The bank is located at the Croatian Institute for Brain Research. http://www.hiim.hr/nova
Glossary Links
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Cite this page: Hill, M.A. (2024, June 15) Embryology Neural - Cerebrum Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Neural_-_Cerebrum_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G