View source for Paper - The human brain at stages 18-20 including the choroid plexuses and the amygdaloid and septal nuclei (1990)

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|[[File:Mark_Hill.jpg|50px|left]] This 1990 paper by Müller and O'Rahilly uses the [[Carnegie Collection]] embryos to characterise the development of the {{ventricular}} system and choroid plexuses during the embryonic period. Note only a modified version of the abstract is shown online for educational purposes.
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Also by this author: {{Ref-O'RahillyMuller1990b}}
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PMID: 2268071 DOI: 10.1007/bf00185521
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:'''Modern Notes:''' {{Ventricular}}

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{{Historic Disclaimer}}
=The Human Brain at Stages 18-20, including the Choroid Plexuses and the Amygdaloid and Septal Nuclei=
[[File:Fabiola Müller.jpg|thumb|150px|alt=Fabiola Müller|link=Embryology History - Fabiola Müller|Fabiola Müller]]
[[File:Ronan O'Rahilly 1987.jpg|thumb|150px|alt=Ronan O'Rahilly 1987|link=Embryology History - Ronan O'Rahilly|Ronan O'Rahilly (1987 Carnegie Labs)]]
[[Embryology History - Fabiola Müller|Müller F.]] and [[Embryology History - Ronan O'Rahilly|O'Rahilly R.]]

Carnegie Laboratories of Embryology, California Primate Research Center, Davis.

==Abstract==

The development of the human brain during the seventh embryonic week was studied in serial sections of 88 embryos, and graphic reconstructions were prepared. From stages {{CS18}}, {{CS19}} and {{CS20}} the cerebral hemispheres expand rapidly and become more and more distinct entities. The longitudinal fissure between them occupies approximately half of their rostrocaudal extent. 


In stage {{CS20}} they have progressed so far in organization that functional aspects (based on synapses in the primordial plexiform layer) are of importance. An advanced differentiation is also present in the amygdaloid body, which has at least four individual nuclei, and in the forebrain septum, which shows the nucleus of the diagonal band and the medial septal nucleus. This has a bearing on recent experimental studies that document the fundamental role of the septal nuclei with regard to behavioural and cognitive functions. Fibre connections between septal nuclei and hippocampus have appeared. A definitive internal capsule, however, is not yet present. The main connections with {{diencephalon}} and other parts of the brain are chiefly by fibres to or from the amygdaloid body by way of the lateral forebrain bundle. 


The olfactory areas are connected with the habenular nuclei by a well developed stria medullaris thalami. Globus pallidus externus, entopeduncular nucleus, and subthalamic nucleus are prominent features in the subthalamus. The main nucleus of the oculomotor nerve shows a dorsolateral and a ventromedial portion. The rhombic lip is mitotically active in all parts of the rhombencephalon, and seems to participate significantly in the formation of the intermediate layer of the {{cerebellum}} and of the cochlear nuclei. The sensory nucleus of the trigeminal nerve has appeared. In the cerebellum the cell layer thought to contain the future Purkinje cells develops. The cerebellar plate is organized into external and internal bulges, and is now connected with {{midbrain}} and {{hindbrain}} through fibre bundles. The area thought to be the dentate nucleus and the supposed floccular region are especially rich in fibres. 


The accessory olivary nucleus appears in stage {{CS19}}, and accessory nuclei of the abducent and hypoglossal nerves are evident in stage {{CS20}}. The {{choroid plexus}}es of the fourth and lateral ventricles have appeared. In view of their advanced features, the study of embryos of stages 19-21 becomes increasingly relevant to questions of tissue transplantation.


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[[Category:Historic Embryology]][[Category:1990's]][[Category:Ronan O'Rahilly]][[Category:Human Embryo]][[Category:Carnegie Collection]][[Category:Neural]][[Category:Ventricular System]][[Category:Carnegie Stage 18]][[Category:Carnegie Stage 10]][[Category:Carnegie Stage 20]]