Ontogenesis cerebri humani

Cave: notitiae huius paginae nec praescriptiones nec consilia medica sunt.

Ontogenesis cerebri humani describit in hominibus ordinem ab conceptione evolutionis cerebri, sic ad generationem (neurogenesem) cellularum nervalium, incrementum migrationemque eorum velut nexus inter se spectans. Partes in embryogenesi ab hebdomade tertia post gestationem^[1], partes post partum fiunt. Ontogenesis inter partes neurona generandi, migrationum neuronorum et maturationem dividito. Postremo cerebro humano centum millenia milia neuronorum sunt^[2]. Post maturationem cerebro plus quam sexagies millies millena milia nexus (synapses) sunt.

Contra cerebra specierum aliarum mammaliarum cerebrum humanum expansionem neocorticis differentiationemque ostendit. Pro eo incrementum microcircuituum, ita varietatis functionum cerebralium formare contigit. Nimirum, ut scientia nexus inter cerebrum humanum et evolutionem culturae humanae posuerunt^[3].

Impedimenta ontogenesis maturius vel multis annis post mala etiam gravia ut autismum, schizophreniam, depressionem excitent.

Gradus ontogenesis cerebri humani

Mensurae embryonicae idoneae sunt vel aetas a foecundatione vel post conceptionem (p. c.), quae sunt tempora a zygoti formatione, duratio tunc graviditatis est iam duo hebdomades^[4]. Tempora haec praenatalia diebus embryonicis (abbreviatura littera "E") exprimantur; quod est "E16" diei decimi sexti respondere.

I. Post fertilizatio: zygotum, morula, blastula (E1-E12)

Post fertilizationem gametis duabus fusatis zygotum cellula eukaryotica binarum gametarum formatur. Zygotum cingitur zona pellucida globulum formans. Deinde morula, blastula oriuntur. Hoc tempore cellulae neurales nondum sunt.

Post foecundationem primo zygotum formatur.
Zygotum
Blastomerus cellularum binarum (sinistra).
Blastocystus in utero et iuxta endometrio.
incrementum morulae
Blastulatio: de morula ad blastulam.

II. Gastrula et celluae progenitores (E13-E15)

Die decimo tertio post foecundationem ex blastula strati unius tunc gastrula trium, (ectodermatis enim et mesodermatis et entodermatis) constituitur, gastrulatio vocatur. Ex materie ectodermatis ab hoc tempore celluae progenitores systematis nervosi nascuntur. Neurogenesis vero, productio neuronorum, serius, ab die quadragesimo secundo demum orditur.

Gastrulatio: formatio entodermatis (rubre).

III. De plica et lamina et crista ad formationem tubae neuralis (neurulatio, E16-E28)

Die decimo sexto post foecundationem (E16) plica neuralis formatur. Eo biduo post (E18) lamina neuralis generatur. Tum ab die vicesimo quarto (E24) per formationem anguli inferioris labra conveniunt, crista neuralis. Usque ad hebdomadem quartam tubae neuralis formatio est prima cum structura visibili neurali plena (E28). Transformatio de plica neurali in tubam neuralem neurulatio nominatur. Nunc cerebro embryonico vesiculae a neuroepithelio circumventae tres sunt, prosencephali enim, et mesencephali et rhombencephali.

Formatio cristae neuralis et tubae neuralis.
Embryo cum prosencephalo et mesencephalo et rhombencephalo (E28).

IV. De tres ad quinque vesiculas cerebri (E29-E35)

Ex prosencephalo oriuntur vesiculae telenephali et diencephali, ex rhombencephalo metencephali velut myelencephali.

V. Incrementum radiale (proliferatio) cum neurogenesi et apoptosi

Intra tubam neuralem neurogenesis in zona ventriculari, iuxta ventriculos, fit. Proliferationi et migrationi neuronorum novorum machinatio mira ostendit, migratio nuclearis intercinetica (MNI)^[5]^[6] vocatur, quo cellulae inter superficies zonae ventricularis basalem (gradu G1) et apicalem (gradibus G2, M) commovent^[7].

Formatio sulcorum corticalium

Formationis sulcorum diversae hypotheses dictae sunt^[8]:

Expansio lateralis substantiae griseae communiter cum sulcos substantiae alba formandis
Variationes expansionis stratorum diversorum corticalium
Tensio iuxta longitudinem axonum crescentium

Incrementum postnatale

Usque ad duo annos post partem perseverat incrementum, hoc tempore voluminis cerebri amplum est^[9].

Zonae proliferativae

In cerebro humano cellulae novae neuronales in zonae duae mitosi oriuntur, quae sunt zonae ventriculares et zonae subventriculares.

Damnum neurogenesis hypoplasiam perficere potest, migrationis ectopiam (locos non idoneos), axogenesis et dendrogenesis et synaptogenesis dysplasiam cum nexibus neuronalibus non idoneis.

Zona ventricularis

Omnes zonae ventriculares cum neuroepithelio per totius parietes systematis ventricularium reperiuntur. Ibi generatio neuronorum novorum de cellulis progenitoribus (vel cellulae neuroepitheliales dictum) superficiei apicalis zonae ventricularis fit^[10]. Ex neuroepithelii cellulis cellulae neuronales telencephali oriuntur.

Zona subventricularis

Zonae subventriculares sunt zonae proliferativae secundariae. Eae iuxta zonas ventriculares locatae sunt.

Neurogenesis - generatio neuronorum novorum

Conferatur pagina principalis: Neurogenesis.

Cerebro humano multa miliarda cellularum neuralium sunt. Pleraque in media gestationis generantur^[11].

Cellula glialis radialis

Cellulae neuroepitheliales (sive cellulae progenitores neurales^[12]), ex quibus imprimis cellulae gliales radiales derivantur, tres formas divisionum ostendunt:

divisionem proliferantem symmetricam — cum generatione duarum cellularum neuroepithelialium
divisionem non symmetricam — cum generatione singularum cellularum et neuroepithelialis et neuronalis
divisionem differentem symmetricam — cum generatione duarum cellularum neuronalium

His cellulis glialibus radialibus formae bipolares cum singulis processibus per tota strata corticalia currentibus sunt^[13].

Angiogenesis - generatio vasorum cerebralium

Generatio novorum vasorum cerebri ab hebdomade tertia coepit. primo extra embryonem, ex cellulis mesenchymatis insulae haemangioblasti nascuntur, deinde ab insularum marginibus angioblasti, postremo cellulae endotheliales, demum parietes vasorum formantes.

Angiogenesis arterialis

Intra embryonem initio duae aortae embryonales oriuntur, ex quibus plures surculi intersegmentales formantur. Paulo post aorta duplex in unam, adultam, confundit.

Ex ramulis intercostalibus septimis et arteria subclavia et arteria vertebralis (partis posterioris cerebri) formantur.

Gubernatio genetica

Proteina certa cerebro incrementi gubernant. Nimirum in ontogenesis cursu diversa gena temporibus distinctis leguntur vel negleguntur. Ergo iam mature post mitotem destinata loci functionisque cuiusque cellulae novae neuralis imponi videtur. Etiam divisionem cerebri sic fit. Per exemplum proteinum GBX-2 rhombomeres partes cerebri incrementi mesencephali promittit.

Nexus interni

Notae

↑ Stiles J, Jernigan TL (2010). "The Basics of Brain Development". Neuropsychol Rev 20 (4): 327-48
↑ Pakkenberg B., Gundersen H. J. (1997). "Neocortical neuron number in humans: effect of sex and age". J Comp Neurol 384 (2): 312-20
↑ DeFelipe J. (Mai 2011). "The evolution of the brain, the human nature of cortical circuits, and intellectual creativity". Frontiers in neuroanatomy 5: 29 doi:10.3389/fnana.2011.00029
↑ Calculationis aetatis gestationis enim aetati a foecundatio 14 dies addito.
↑ Del Bene F (2011). "Interkinetic nuclear migration: cell cycle on the move". EMBO J 30 (9): 1676-7
↑ Spear PC, Erickson CA (2012). "Interkinetic Nuclear Migration: A Mysterious Process in Search of a Function". Dev Growth Differ 54 (3): 306-16
↑ Miyata M, Okamoto M, Shinoda T, Kawaguchi (2014). "Interkinetic nuclear migration generates and opposes ventricular-zone crowding: insight into tissue mechanics". Front Cell Neurosci 8: 473
↑ Mota B., Herculano-Houzel S. (Feb 2012). "How the cortex gets its folds: an inside-out, connectivity-driven model for the scaling of Mammalian cortical folding". Frontiers in neuroanatomy 6: 3
↑ Knickmeyer RC, Gouttard S, Kang C, Evans D, Wilber K, Smith JK, Hamer RM, Lin W, Gerig G, Gilmore JH (2008). "A structural MRI study of human brain development from birth to 2 years". J Neurosci 28 (47): 12176-82
↑ Haubensak W., Attardo A., Denk W., Huttner W. B. (Mar 2004). "Neurons arise in the basal neuroepithelium of the early mammalian telencephalon: a major site of neurogenesis". Proceedings of the national academy of sciences 101 (9): 3196-201
↑ Bayer SA, Altman J, Russo RJ, Zhang X (1993). "Timetables of neurogenesis in the human brain based on experimentally determined patterns in the rat". Neurotoxicology 14 (1): 83-144
↑ Martínez-Cerdeño V., Noctor S. C. (Dec 2018). "Neural Progenitor Cell Terminology". Frontiers in neuroanatomy 12: 104
↑ Tamamaki N., Nakamura K., Okamoto K., Kaneko T. (Sep 2001). "Radial glia is a progenitor of neocortical neurons in the developing cerebral cortex". Neuroscience research 41 (1): 51-60

Nexus externi

Universitas Roffae: intellegere cerebra adulescentia. (Anglice)

[1] Stiles J, Jernigan TL (2010). "The Basics of Brain Development". Neuropsychol Rev 20 (4): 327-48

[2] Pakkenberg B., Gundersen H. J. (1997). "Neocortical neuron number in humans: effect of sex and age". J Comp Neurol 384 (2): 312-20

[3] DeFelipe J. (Mai 2011). "The evolution of the brain, the human nature of cortical circuits, and intellectual creativity". Frontiers in neuroanatomy 5: 29 doi:10.3389/fnana.2011.00029

[4] Calculationis aetatis gestationis enim aetati a foecundatio 14 dies addito.

[5] Del Bene F (2011). "Interkinetic nuclear migration: cell cycle on the move". EMBO J 30 (9): 1676-7

[6] Spear PC, Erickson CA (2012). "Interkinetic Nuclear Migration: A Mysterious Process in Search of a Function". Dev Growth Differ 54 (3): 306-16

[7] Miyata M, Okamoto M, Shinoda T, Kawaguchi (2014). "Interkinetic nuclear migration generates and opposes ventricular-zone crowding: insight into tissue mechanics". Front Cell Neurosci 8: 473

[8] Mota B., Herculano-Houzel S. (Feb 2012). "How the cortex gets its folds: an inside-out, connectivity-driven model for the scaling of Mammalian cortical folding". Frontiers in neuroanatomy 6: 3

[9] Knickmeyer RC, Gouttard S, Kang C, Evans D, Wilber K, Smith JK, Hamer RM, Lin W, Gerig G, Gilmore JH (2008). "A structural MRI study of human brain development from birth to 2 years". J Neurosci 28 (47): 12176-82

[10] Haubensak W., Attardo A., Denk W., Huttner W. B. (Mar 2004). "Neurons arise in the basal neuroepithelium of the early mammalian telencephalon: a major site of neurogenesis". Proceedings of the national academy of sciences 101 (9): 3196-201

[11] Bayer SA, Altman J, Russo RJ, Zhang X (1993). "Timetables of neurogenesis in the human brain based on experimentally determined patterns in the rat". Neurotoxicology 14 (1): 83-144

[12] Martínez-Cerdeño V., Noctor S. C. (Dec 2018). "Neural Progenitor Cell Terminology". Frontiers in neuroanatomy 12: 104

[13] Tamamaki N., Nakamura K., Okamoto K., Kaneko T. (Sep 2001). "Radial glia is a progenitor of neocortical neurons in the developing cerebral cortex". Neuroscience research 41 (1): 51-60

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