Editing Ventricular system (section)

=== Development === <!--Development of ventricular system redirects here-->
The structures of the ventricular system are [[embryogenesis|embryologically]] derived from the [[neural canal]], the centre of the [[neural tube]].{{cn|date=January 2024}}

As the part of the primitive neural tube that will develop into the [[brainstem]], the neural canal expands dorsally and laterally, creating the [[fourth ventricle]], whereas the neural canal that does not expand and remains the same at the level of the midbrain superior to the fourth ventricle forms the [[cerebral aqueduct]]. The fourth ventricle narrows at the [[obex]] (in the caudal medulla), to become the [[central canal]] of the [[spinal cord]].{{cn|date=January 2024}}

In more detail, around the third week of development, the embryo is a three-layered disc. The embryo is covered on the [[:wikt:dorsal|dorsal]] surface by a layer of cells called [[ectoderm]]. In the middle of the dorsal surface of the embryo is a linear structure called the [[notochord]]. As the ectoderm proliferates, the notochord is dragged into the middle of the developing embryo.<ref name=LARSEN2009>{{cite book|first=Gary C. |last=Schoenwolf|title=Larsen's human embryology|year=2009|publisher=Churchill Livingstone/Elsevier|location=Philadelphia|isbn=9780443068119|chapter="Development of the Brain and Cranial Nerves"|edition=4th}}</ref>

As the [[Brain#Development|brain develops]], by the fourth week of embryological development three swellings known as [[brain vesicle]]s have formed within the embryo around the canal, near where the head will develop. The three primary brain vesicles represent different components of the [[central nervous system]]: the [[prosencephalon]], [[mesencephalon]] and [[rhombencephalon]]. These in turn divide into five secondary vesicles. As these sections develop around the neural canal, the inner neural canal becomes known as ''primitive'' ventricles. These form the ventricular system of the brain:<ref name=LARSEN2009 />  The [[neural stem cells]] of the developing brain, principally [[radial glial cell]]s, line the developing ventricular system in a transient zone called the [[ventricular zone]].<ref>{{cite journal|last1=Rakic|first1=P|title=Evolution of the neocortex: a perspective from developmental biology.|journal=Nature Reviews. Neuroscience|date=October 2009|volume=10|issue=10|pages=724–35|pmid=19763105|doi=10.1038/nrn2719|pmc=2913577}}</ref>
* The [[prosencephalon]] divides into the [[telencephalon]], which forms the [[cerebral cortex|cortex]] of the developed brain, and the [[diencephalon]]. The ventricles contained within the telencephalon become the [[lateral ventricles]], and the ventricles within the [[diencephalon]] become the [[third ventricle]].
* The rhombencephalon divides into a [[metencephalon]] and [[myelencephalon]]. The ventricles contained within the rhombencephalon become the [[fourth ventricle]], and the ventricles contained within the mesencephalon become the [[aqueduct of Sylvius]].

Separating the anterior horns of the lateral ventricles is the [[septum pellucidum]]: a thin, triangular, vertical membrane which runs as a sheet from the [[corpus callosum]] down to the [[fornix of the brain|fornix]]. During the third month of fetal development, a space forms between two septal laminae, known as the [[cave of septum pellucidum]] (CSP), which is a marker for fetal neural maldevelopment. During the fifth month of development, the laminae start to close and this closure completes from about three to six months after birth. Fusion of the septal laminae is attributed to rapid development of the [[Alveus of hippocampus|alvei]] of the [[hippocampus]], [[amygdala]], [[septal nuclei]], fornix, corpus callosum and other midline structures. Lack of such limbic development interrupts this posterior-to-anterior fusion, resulting in the continuation of the CSP into adulthood.<ref name="Adrian Raine 2010 p.110">{{cite journal | last1 = Raine | first1 = Adrian | last2 = Lee | first2 = Lydia | last3 = Yang | first3 = Yaling | last4 = Colletti | first4 = Patrick | year = 2010 | title = Neurodevelopmental marker for limbic maldevelopment in antisocial personality disorder and psychopathy". BJPsych | journal = The British Journal of Psychiatry | volume = 197 | issue = 3| pages = 186–192 | doi = 10.1192/bjp.bp.110.078485 | pmid=20807962 | pmc=2930915}}</ref>