Ventricular system and choroid plexuses of the human brain during the embryonic period proper

Abstract

This morphological study, based on serial sections and graphic reconstructions at 4-8 postovulatory weeks (stages 11-23), is believed to be the first account of the ventricular system in staged human embryos. Closure of the caudal neuropore at stage 12 heralds the onset of the ventricular system and separates the ependymal from the amniotic fluid. After the appearance of the optic ventricle at stage 11, the cavity of the telencephalon medium is discernible at stage 13. At stage 14 the future cerebral hemispheres and lateral ventricles begin, and the rhomboid fossa becomes apparent. The medial and lateral ventricular eminences cause indentations in the lateral ventricle by stage 15. The hypothalamic sulcus is evident at stage 16. At stages 17-18 the interventricular foramina are becoming relatively smaller, and cellular accumulations indicate the future choroid villi of the fourth and lateral ventricles. The areae membranaceae rostralis and caudalis are visible in the roof of the fourth ventricle at stage 18, and the paraphysis is appearing. At stage 19 choroid villi are seen in the fourth ventricle, and a mesencephalic evagination (Blindsack) is detectable. Choroid villi are noticeable in the lateral ventricle at stage 20. An olfactory ventricle is present by stage 21. At about stages 21-23 the lateral ventricle has become C-shaped, so that anterior and inferior horns are visible. Several recesses, e.g., the optic, infundibular, and pineal, develop in the third ventricle during the embryonic period. Features of the ventricular system that do not become apparent until the fetal period include the posterior horn of the lateral ventricle, choroid plexus of the third ventricle, suprapineal recess, interthalamic adhesion, aqueduct, and apertures in the roof of the fourth ventricle.

Midline cystic malformations of the brain: imaging diagnosis and classification based on embryologic analysis

“…35,36 The choroid plexus of the lateral ventricle is formed by epithelial lamina, which is derived from the velum transversum at the transition to the diencephalic roof plate (epithelial roof of the third ventricle), together with meninx from the interhemispheric fissure. 38 At the end of the embryonic period (stage 23), pioneer fibers of the corpus callosum pass through the dorsal part of the lamina reuniens (Fig. 10), where the massa commissuralis is formed as the callosal precursor.…”

Dilated Fourth Ventricle in Fetuses with Trisomy 18, Trisomy 13 and Triploidy at 11–13 Weeks’ Gestation

“…At 8–9 weeks’ gestation the roof of the fourth ventricle contains two areas lined by flattened ependymal cells: the anterior or rostral and posterior or caudal membranous areas separated by the plica choroidea, which subsequently develops into the choroid plexus [15]. Cystic malformations in the posterior fossa have been classified on the basis of their embryological origin into those of the rostral area with abnormal development of the cerebellum as in DWM and those of the caudal area with inadequate opening of the foramina of Magendie and Luschka, which are often transient and of no pathological significance [16,17,18].…”

Dural Arteriovenous Shunts

“…7 In the same period (corresponding to Paget's 5-mm stage embryo), the blood traversing the capillary network at the surface of the brain is drained on either side by 3 "meningeal" (leptomeningeal) venous plexuses arranged craniocaudally (anterior, middle, and posterior); cranially, these open into a corresponding "primary head sinus" (epidural) and which will further develop by coalescence into "primitive sinuses." 8,9 The development of the choroid plexus starts at Paget's 8-to 11-mm stage embryo 10 with venous drainage into the median prosencephalic vein, which functions as the venous drainage route for the early immature brain and choroid plexuses. Secondarily, it may collect the deep cerebral venous afferents and basal vein, thereafter becoming the great cerebral vein or vein of Galen.…”