Embryology of the Vascular System ECNR 2016 UCL Institute of Neurology Queen Square, London Endothelial cells Pericytes Smooth muscle Connective cells Charles Raybaud Primitive streak neural crest Ectoderm neural tube Mesoderm pharyngeal pharyngeal endoderm endoderm Endoderm endothelial cells endothelial cells NEURAL CREST CELLS (NCC) Arteries of the pharyngeal arches 1st pharyngealpouch Endoderm Internal carotid Dorsal aorta Vitelline arteries Arterial vitelline plexus Umbilical arteries Larsen, Human Embryology 3 Metameric Territories from Which Arteries Derive A: rostral mesoderm supplies Prosencephalon B: middle mesoderm supplies Diencephalon 1st branchial arch derivates C: caudal medoderm supplies Mesencephalon Metencephalom 2nd brachial arch derivates Development of Cerebral Arteries Endothelial Vasculogenesis Vascularisation of the brain adapts continuously to changes in shape size metabolic demand Blood supply adapts metabolic demand of brain activity Morphological changes in neural tissue reshape the arterial tree week 4 week 5 Raybaud Neurosurg Clin N AM 2010 Embryology of Carotid System Embryological Segments of ICA Regressions 1st and 2nd aortic arches Formation of ICA prim. mandibular a. caroticotympanic a. 1 ventral aorta 2 dorsal aorta Embryonic ICA segments 1 cervical 15 dorsal ophthalmic a. 2 ascending intra-petrous 16 ventral ophthalmic a. 3 horizontal intra-petrous 17 MCA 4 ascending foramen lacerum 18 ACA 5 horizonantal intracavernous 20 anterior choroidal a. 6 clinoid 7 termination Intracranial ICA Connection of Anterior and Posterior Circulation Week 5 Telencephalic portion of brain Diencephalic Termination Cranial portion of brain division phylogenetic Mesencephalic ICA portion of brain Termination Caudal division Raybaud Neurosurg Clin N AM 2010 PChorA Collic a Sup cer a aica pica anterior component of the (limbic) ring : anterior cerebral artery posterior component of the (limbic) ring : anterior choroidal artery Simultaneously the both - supply the choroid plexus and anastomose at the level of the ventral longitudinal axes fuses in the midline to form the interventricular foramen (Monro) basilar artery and the ASpinalA - present telencephalic branches anastomosing at the surface of the vesicles Phylogenetic Aspects Embryology of Cerebral Arteries: Main Concepts The ACA is a terminal branch of the ICA with various opotions for midline anastomoses The MCA is a branch of the ACA developing after the recurrent artery of Heubner The anterior choroidal artery is an old artery and anastomosis with the ACA, supplying the limbic system. The PCA belongs to caudal division of ICA It will annex cortical territory from the anterior choroidal artery The basilar artery results form cranio-caudal fusion of the posterior division of the ICA Opossum: Full Limbic Ring Development of Anterior Cerebral Artery Development of Middle Cerebral Artery Primitive olfactory artery as MCA (2) arises from ICA, initial termination of ICA distal to anterior choroidal artery (1) ACA is continuation MCA extends laterally over primitive olfactory artery , surface on brain extending upwards and Depression and invagination backwards over lateral aspect of brain Regression of primitive (formation of opercula and olfactory artery insula) is followed by MCA Development of Posterior Cerebral Artery Aberrant ICA Foetal Gives rise mesencephalic, diencephalic and posterior choroidal and cortical vessels Shifts dominant supply to basilar artery with partial regression of PCOM artery Aberrant ICA Anterior Communicating Artery Complex involution of the normal cervical portion (first embryonic segment) of the ICA Enlargement of collateral pathways inferior tympanic artery (ITA) caroticotympanic artery (CTA) ACA Variants Foetal L PCA Foetal R PCA Fusion of Basilar Tip- Possibilities Symmetrical Cranial Fusion Symmetric Caudal Fusion Revista Argentina de Neurocirugia 2013 Revista Argentina de Neurocirugia 2013 Asymmetrical Caudal Fusion Cobrahead Tip Revista Argentina de Neurocirugia 2013 Basilar Tip Configuration on DSA Vertebral and Basilar Variants Normal Basilar Tip: 30.4% Cranial Symmetrical 26.1% Caudal Symmetrical 43.5% Caudal asymmetrical Basilar Tip Aneurysms 9 % Cranial symmetrical 51% caudal symmetrical 40% Caudal asymmetrical Campos et al Interv Neuroradiol.1998 Basilar Fenestration Vertebral Artery Fenestration distal proximal PICA Termination of R Vertebral Artery Persistent Vestigial Arteries Embryonal Pattern tga trigeminal artery oa otic artery hga hypoglossal artery paa proatlantal artery Hypoglossal Artery Trigeminal Artery Hypoglossal Artery Trigeminal Artery Choroidal Stage Tela choroidea and plexuses drained by a single, median dorsal bridging vein (median prosencephalic vein of Markowski) that antecedes the development of the internal cerebral veins and vein of Galen Week 6: Three Venous Plexuses (ant, mid and post) Week 8 and 9 mpvm = median prosencephalic vein of Markowski (7) dv = diencephalic vein ts = transverse sinus 5 + 6 = sigmoid sinus OC = Otic Capsule Month 3 Vein of Galen Aneurysm early late 11 = middle cerebral vein 12 = superior sagittal sinus 13 = tentorial plexus 14 = internal cerebral veins Vein of Galen Aneurysmal Malformation (VGAM) ASL in Vein of Galen Aneurysmal Malformation (VGAM) In utero day 1 Courtesy of Madgalena Sokolska Neonate SWI A Special Thank You To Majda Thurnher Timo Krings Karel Ter Brugge George Rodesch.