Talk:Cardiovascular System - Blood Vessel Development

Specification of arterial, venous, and lymphatic endothelial cells during embryonic development

Kume T. Histol Histopathol. 2010 May;25(5):637-46. Review.

The groundbreaking discovery about arterial and venous expression of ephrinB2 and EphB4, respectively, in early embryonic development has led to a new paradigm for vascular research, providing compelling evidence that arterial and venous endothelial cells are established by genetic mechanisms before circulation begins. For arterial specification, vascular endothelial growth factor (VEGF) induces expression of Notch signaling genes, including Notch1 and its ligand, Delta-like 4 (Dll4), and Foxc1 and Foxc2 transcription factors directly regulate Dll4 expression. Upon activation of Notch signaling, the Notch downstream genes, Hey1/2 in mice or gridlock in zebrafish, further promote arterial differentiation. On the other hand, the orphan nuclear receptor COUP-TFII is a determinant factor for venous specification by inhibiting expression of arterial specific genes, including Nrp1 and Notch. After arterial and venous endothelial cells differentiate, a subpopulation of venous endothelial cells is thought to become competent to acquire lymphatic endothelial cell fate by progressively expressing the transcription factors Sox18 and Prox1 to differentiate into lymphatic endothelial cells. Therefore, it has now evident that arterial-venous cell fate determination and subsequent lymphatic development are regulated by the multi-step regulatory system associated with the key signaling pathways and transcription factors. Furthermore, new signaling molecules as additional regulators in these processes have recently been identified. As the mechanistic basis for a link between signaling pathways and transcriptional networks in arterial, venous and lymphatic endothelial cells begins to be uncovered, it is now time to summarize the literature on this exciting topic and provide perspectives for future research in the field.

PMID: 20238301 http://www.ncbi.nlm.nih.gov/pubmed/20238301

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2899674

Fetal anatomy of the human carotid sheath and structures in and around it.

Anat Rec (Hoboken). 2010 Mar;293(3):438-45.

Miyake N, Hayashi S, Kawase T, Cho BH, Murakami G, Fujimiya M, Kitano H.

Department of Otorhinolaryngology, Tottori University, Yonago, Japan. Abstract The aim of this study was to find basic rules governing the morphological development of the typical neurovascular sheath. We carried out histological examination of 15 paraffin-embedded mid-term fetuses at 9-25 weeks of gestation (three fetuses each at 9, 12, 15, 20, and 25 weeks). As the result, the vagus nerve showed a high propensity to change its topographical relationship with the common carotid artery (CCA) during 9-20 weeks of gestation: that is, from a primitive ventral course to a final dorsal course. The adventitia of the great arteries, which was distinct from other fascial structures, became evident by 15 weeks. The carotid sheath appeared at and after 20 weeks: it was clearly separated from the prevertebral lamina of the deep cervical fasciae, but fused with the pretracheal lamina covering the strap muscles. Thus the carotid sheath, as well as the topographical relationships of structures within it, seems to become established much later than the prevertebral and pretracheal laminae of the deep cervical fasciae. However, the adventitia of the cervical great arteries consistently becomes evident much earlier than the sheath, and it seems to be regarded as one of the basic components of the fetal deep cervical fasciae.

PMID: 20169562