Embryonic vascular development

Knudsen TB, Kleinstreuer NC (2012) Disruption of embryonic vascular development in predictive toxicology. Birth Defects Res C Embryo Today 93 312-323... 

We have, in the studies summarized in this chapter, explored some of the contributions that cells building up human blood vessel walls can provide to embryonic development and post-natal tissue repair. Sabin (1920) first proposed that blood cells sprout from embryonic vascular endothelium but it is only at the end of the century that investigators employed cell marking, cell sorting. 

Kuro-o M, Nagai R, Nakahara K, Katoh H, Tsai RC, Tsuchimochi H, Yazaki YH, Ohkubo H, Takaku F (1991) cDNA cloning of a myosin heavy chain isoform in embryonic smooth muscle and its expression during vascular development and in arteriosclerosis. J Biol Chem 266 3768-3773... 

Gerecht-Nir, S., Osenberg, S., Nevo, O., Ziskind, A., Coleman, R., and Itskovitz-Eldor, J. 2004. Vascular development in early human embryos and in teratomas derived from human embryonic stem cells. 

At about four months gestation, mesenchymal cells emanating from the central hyaloid vessel at the optic disc invade the inner layers of the retina. These endothelial complexes develop into capillaries as vascularization proceeds anteriorly in all directions towards the ora serrata from the optic nerve. As this progresses, so the embryonic hyaloid vessels in the vitreous undeigo regression. These retinal vessels do not, however, reach the most anterior portion of the retina until 8 months gestation and the anterior temporal retinal periphery, ferthest removed from the optic nerve, is not vascularized until about full term (Flower and Patz, 1971). 

The seeds of dicotyledonous plants have two cotyledons, or seed leaves, which are part of the embryo. The cotyledons usually are the main storage tissue, although in some plants (such as castor bean) the endosperm also has a storage function. During development in the field, seeds gradually accumulate storage oils, proteins and carbohydrates (Table 3.1). In the seed, the cotyledon structure is relatively simple. The remainder of the embryo, the embryonic axis, consists mostly of undifferentiated cells, but provascular tissue can be detected that develops into vascular tissue in the seedling. 

The cerebral endothelial cells of the blood-brain barrier originate from the middle germinal sheet of the embryo, the mesoderm [17]. Concomitant with migration and proliferation of capillary endothelial cells during formation of the cerebral vascular network occurs the imprinting of the cells. Thereby, induction by the cellular surrounding plays an important role [18-21], The relevance of the cellular environment for the development of the barrier function of cerebral microvessels was first demonstrated by Stewart and Wiley [22], who transplanted embryonic brain tissue of a quail into embryonic gut tissue of chicken and vice versa. The cerebral transplant was vascularized by intestinal vessels, in which properties of the blood-brain barrier had been induced. In transplanted brain vessels, however, no characteristics of a barrier could be demonstrated, due to the lack of a neuronal environment. These results indicated that the cerebral microvessels are of extraneuronal origin, with properties that are induced by the cellular environment. In addition, brain tissue has the capability to induce blood-brain barrier characteristics also in noncerebral vascular tissue [23],... 

Miquerol L, Langille BL, Nagy A. Embryonic development is disrupted by modest increases in vascular endothelial growth factor gene expression. Development 2000 127 3941-3946. 

Hellstrom M, Kalen M, Lindahl P, Abramsson A, Betsholtz C (1999) Role of PDGF-B and PDGFR-beta in recruitment of vascular smooth muscle cells and pericytes during embryonic blood vessel formation in the mouse. Development, 126(14) 3047-3055. 

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