Angiogenic potential of the avian somite

Abstract

We have studied the angiogenic potential of the unsegmented paraxial mesoderm and epithelial somites of the trunk with homotopical grafts between quail and chick embryos. Quail endothelial cells of the grafts were stained with the QH-1 antibody after 1-6 days of reincubation. The unsegmented paraxial mesoderm and all parts of the epithelial somite were found to contain angioblasts which develop into QH-1 positive endothelial cells. These cells are incorporated into the lining of the host's blood vessels such as the perineural vascular plexus and the dorsal branches of the aorta. There is a certain preference as concerns the location of endothelial cells derived from different parts of the somites. Angioblasts from ventral somite halves are mainly found in ventrolateral blood vessels. Those from dorsomedial quadrants form vessels in the dermis of the back, and those from dorsolateral quadrants can be found in the ventrolateral body wall and the wing. With the exception of the dorsal perineural vascular plexus, angioblasts do not cross the median plane of the body. This shows that, although angioblasts migrate extensively, there is bilaterality of the vascular system in the trunk. It remains to be studied whether the notochord plays a role in the establishment of this bilaterality. 0 1995 Wiley-Liss, Inc.

Neurovascular development

“…Quail-chick chimeras were analyzed using QH1 to identify vessels deriving from grafts, and the source of endothelial cells contributing to the PNVP and vessels invading the neural tube was shown to be primarily lateral plate mesoderm, with contributions from somitic angioblasts. [7][8][9] We extended these studies by analyzing mouse-quail chimeras that had orthotopic grafts of mouse somitic mesoderm in quail hosts. 10 These studies showed that mouse angioblasts could also migrate and contribute to the PNVP in the avian embryo, indicating that the neural-derived patterning cues crossed species.…”

Expression pattern of Vasohibin during chick development

“…Expression in the dorsal neural tube, IM, and LPM remains the same throughout development. Numerous angioblasts are reported to be present in the lateral part of the somite, participating in the formation of the blood and lymphatic vessel in the limb and ventro-lateral body wall (Lance-Jones, 1988;Noden, 1989;Wilting et al, 1995). Thus, expression of Vasohibin in lateral plate and limb mesoderm might reflect a possible role in the regulation of angioblast migration from the somite.…”

Cell lineages and early patterns of embryonic CNS vascularization

“…In all regions, EC are exclusively derived from mesoderm, be it segmented (trunk) 14 or unsegmented (head). 15 Of note, the dorsal aortas arise as paired structures from confluent blood islands and subsequently fuse into a single aorta along the a-p axis.…”

“…The latter will give rise to striated muscles and dermis, whereas the former will give rise to the vertebral column. In addition to these fates, cells of all somite compartments 14,19,20 (and not blood islands), will give rise to EC in the body wall and extremities-and in the NT. In addition, PC and vSMC can also be derived from somite cells.…”

“…The enormous migratory capacity of (mouse and avian) somite-derived EC has been demonstrated repeatedly. 14,19,20,44 Most important, these migrating cells do not appear to follow any VEGF gradients and build vascular plexuses where there is little or no hypoxia. From the viewpoint of the migrating or sprouting EC, the NT represents a structure which is difficult to enter: there is a basal lamina around the neural epithelium, and there is no classical extracellular matrix, rich in fibronectin and other migration promoting molecules, inside the NT.…”