Neural - Pons Development

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Introduction

Fetal brain showing developing pons
Fetal Head showing developing Pons.
Right lateral view of adult brain showing Pons
Adult brain showing Pons.

(Latin, pons = "bridge") A brain stem region within the central nervous system, anatomically lying above the medulla before the nervous system becomes the spinal cord.

Historically, the pons was described as originating from rhombomere r1 to r6, molecular studies have shown that the basilar pons is located only within rhombomeres r3 and r4.[1]


Neural development is one of the earliest systems to begin and the last to be completed after birth. This development 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. The early central nervous system begins as a simple neural plate that folds to form a groove then tube, open initially at each end. Failure of these opening to close contributes a major class of neural abnormalities (neural tube defects). Within the neural tube stem cells generate the 2 major classes of cells that make the majority of the nervous system : neurons and glia. Both these classes of cells differentiate into many different types generated with highly specialized functions and shapes. This section covers the establishment of neural populations, the inductive influences of surrounding tissues and the sequential generation of neurons establishing the layered structure seen in the brain and spinal cord.


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 Parts: neural | prosencephalon | telencephalon cerebrum | amygdala | hippocampus | basal ganglia | diencephalon | epithalamus | thalamus | hypothalamus‎ | pituitary | pineal | mesencephalon | tectum | rhombencephalon | metencephalon | pons | cerebellum | myelencephalon | medulla oblongata | spinal cord | neural vascular | ventricular | lateral ventricles | third ventricle | cerebral aqueduct | fourth ventricle | central canal | meninges | Category:Ventricular System | Category:Neural

Some Recent Findings

Stage10 sem6.jpg

Brain stem subdivisions

  • Review - Time for Radical Changes in Brain Stem Nomenclature-Applying the Lessons From Developmental Gene Patterns[1] "The traditional subdivision of the brain stem into midbrain, pons, and medulla oblongata is based purely on the external appearance of the human brain stem. There is an urgent need to update the names of brain stem structures to be consistent with the discovery of rhomobomeric segmentation based on gene expression. The most important mistakes are the belief that the pons occupies the upper half of the hindbrain, the failure to recognize the isthmus as the first segment of the hindbrain, and the mistaken inclusion of diencephalic structures in the midbrain. The new nomenclature will apply to all mammals. This essay recommends a new brain stem nomenclature based on developmental gene expression, progeny analysis, and fate mapping."
  • The Long Journey of Pontine Nuclei Neurons: From Rhombic Lip to Cortico-Ponto-Cerebellar Circuitry[2] "The pontine nuclei (PN) are the largest of the precerebellar nuclei, neuronal assemblies in the hindbrain providing principal input to the cerebellum. The PN are predominantly innervated by the cerebral cortex and project as mossy fibers to the cerebellar hemispheres. Here, we comprehensively review the development of the PN from specification to migration, nucleogenesis and circuit formation. PN neurons originate at the posterior rhombic lip and migrate tangentially crossing several rhombomere derived territories to reach their final position in ventral part of the pons. The developing PN provide a classical example of tangential neuronal migration and a study system for understanding its molecular underpinnings."
  • Postnatal growth of the human pons: a morphometric and immunohistochemical analysis[3] "In the present study, we first performed magnetic resonance imaging (MRI)-based morphometric analyses of the postnatal human pons (0-18 years; n = 6-14/timepoint). Pons volume increased 6-fold from birth to 5 years, followed by continued slower growth throughout childhood. The observed growth was primarily due to expansion of the basis pontis. T2-based MRI analysis suggests that this growth is linked to increased myelination, and histological analysis of myelin basic protein in human postmortem specimens confirmed a dramatic increase in myelination during infancy. ...Together, our data reveal remarkable postnatal growth in the ventral pons, particularly during infancy when cells are most proliferative and myelination increases."


More recent papers  
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Search term: Pons Development | Pons Embryology

Older papers  
These papers originally appeared in the Some Recent Findings table, but as that list grew in length have now been shuffled down to this collapsible table.

See also the Discussion Page for other references listed by year and References on this current page.

  • Development of the pons in human fetuses[4] "Morphometric and histological studies of the pons were performed by light microscopy in 28 cases of externally normal human fetuses ranging from 90 to 246 mm in crown-rump length (CRL) and from 13 to 28 weeks of gestation."
  • Cerebellar haemorrhages and pons development in extremely low birth weight infants[5] "The anteroposterior diameter of the pons was measured manually on the midline sagittal T1 Magnetic Resonance Image ...Cerebellar haemorrhages seem to affect the development of the pons in extremely low birth weight (ELBW) with the youngest gestational age (GA)."
  • Development of the human fetal pons: in utero ultrasonographic study[6] "By using the transfontanel approach, evaluation of the fetal pons is feasible via the mid-sagittal plane. The nomograms developed and the ratio to fetal vermis provides reference data that may be helpful when evaluating anomalies of the brainstem."

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 Development
Neural Tube Primary Vesicles Secondary Vesicles Adult Structures
week 3 week 4 week 5 adult
neural plate
neural groove
neural tube

Brain
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

CNS primary vesicles.jpg

Secondary Vesicles

CNS secondary vesicles.jpg


Fetal Pons

  • 130 -140 mm CRL - first myelinated fibers in each motor root of the trigeminal, abducent, and facial nerves.[4]


Adult Pons MRI

Human- adult brain MRI.jpg

[7]

A T1-weighted sagittal MR image from a control subject, showing the midline structures of the posterior cranial fossa and the brainstem and the cerebellum.
  • d + e = length of clivus
  • S = sphenooccipital synchondrosis
  • d = length of basisphenoid between the top of the dorsum sellae and the sphenooccipital synchondrosis of the clivus
  • e = length of the basiocciput between the synchondrosis and the basion
  • b = length of the hindbrain between the midbrain-pons junction and the medullocervical junction
  • a = angle of the cerebellar tentorium to Twining's line
  • c = length of cerebellar hemisphere
  • DS = top of the dorsum sellae
  • IOP = internal occipital protuberance
  • OP = opisthion; IOP to OP = length of supraocciput
  • B = basion; TW = Twining's line
  • McR (B to OP) = McRae's line

References

  1. 1.0 1.1 Watson C, Bartholomaeus C & Puelles L. (2019). Time for Radical Changes in Brain Stem Nomenclature-Applying the Lessons From Developmental Gene Patterns. Front Neuroanat , 13, 10. PMID: 30809133 DOI.
  2. Kratochwil CF, Maheshwari U & Rijli FM. (2017). The Long Journey of Pontine Nuclei Neurons: From Rhombic Lip to Cortico-Ponto-Cerebellar Circuitry. Front Neural Circuits , 11, 33. PMID: 28567005 DOI.
  3. Tate MC, Lindquist RA, Nguyen T, Sanai N, Barkovich AJ, Huang EJ, Rowitch DH & Alvarez-Buylla A. (2015). Postnatal growth of the human pons: a morphometric and immunohistochemical analysis. J. Comp. Neurol. , 523, 449-62. PMID: 25307966 DOI.
  4. 4.0 4.1 Hatta T, Satow F, Hatta J, Hashimoto R, Udagawa J, Matsumoto A & Otani H. (2007). Development of the pons in human fetuses. Congenit Anom (Kyoto) , 47, 63-7. PMID: 17504389 DOI. Cite error: Invalid <ref> tag; name 'PMID17504389' defined multiple times with different content
  5. Fumagalli M, Ramenghi LA, Righini A, Groppo M, Bassi L, De Carli A, Parazzini C, Triulzi F & Mosca F. (2009). Cerebellar haemorrhages and pons development in extremely low birth weight infants. Front Biosci (Elite Ed) , 1, 537-41. PMID: 19482668
  6. Achiron R, Kivilevitch Z, Lipitz S, Gamzu R, Almog B & Zalel Y. (2004). Development of the human fetal pons: in utero ultrasonographic study. Ultrasound Obstet Gynecol , 24, 506-10. PMID: 15459939 DOI.
  7. Sekula RF, Jannetta PJ, Casey KF, Marchan EM, Sekula LK & McCrady CS. (2005). Dimensions of the posterior fossa in patients symptomatic for Chiari I malformation but without cerebellar tonsillar descent. Cerebrospinal Fluid Res , 2, 11. PMID: 16359556 DOI.

Reviews

Angeles Fernández-Gil M, Palacios-Bote R, Leo-Barahona M & Mora-Encinas JP. (2010). Anatomy of the brainstem: a gaze into the stem of life. Semin. Ultrasound CT MR , 31, 196-219. PMID: 20483389 DOI.

Articles

Gesemann M, Litwack ED, Yee KT, Christen U & O'Leary DD. (2001). Identification of candidate genes for controlling development of the basilar pons by differential display PCR. Mol. Cell. Neurosci. , 18, 1-12. PMID: 11461149 DOI.

Ozawa H & Takashima S. (1998). Immunocytochemical development of transferrin and ferritin immunoreactivity in the human pons and cerebellum. J. Child Neurol. , 13, 59-63. PMID: 9512304 DOI.

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Cite this page: Hill, M.A. (2024, March 19) Embryology Neural - Pons Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Neural_-_Pons_Development

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