Primitive streak

Embryos at the primitive-streak stage (18 h) and at the head-process stage [22 h) were treated with CN at 5 x 10" M for 15 min and examined after further Incubation for 21 h. Primitive-streak embryos had malformations of the brain (81.4%) and of the neural tube (48.7%). Those treated at the head-process stage were unaffected by the CN treatment. Lakshmi attributed the injuries to inhibition of... 

Lakshml treated primitive-streak stage embryos with CN to study the effect on Hensen s node (related to the organization of the embryo). The embryos were incubated for 3 h after treatment the nodes were then excised, washed, and grafted to host chick embryos at the same stage. The results showed an inverse relation between the capacity for Induction of Hensen s node and exposure to CN. 

The inner cell mass gives rise to the epiblast (develops into ectoderm) and the hypoblast (develops into endoderm). Cells of the epiblast migrate toward the midline of the early embryo (Figures 13.4 and 13.5). The primitive streak is active proliferation of the cells with a loss of the basement membrane separating the epiblast and endoderm. The epiblast cells migrate and intermingle with the endoderm cells. The anterior end of... 

In this directed cardiac differentiation protocol, combination of activin A and BMP4 induces a primitive streak-like population and mesoderm in hESCs. The addition of Wnt inhibitor DKK1 induces the cardiac mesoderm formation, while VEGF is included to promote the expansion and maturation of KDR+ population. The additional presence of bFGF supports the continuous expansion of the developing cardiovascular lineages. 

Voiculescu O, Bertocchini F, Wolpert L, Keller RE. Stern CD (2007) The amniote primitive streak is defined by epithelial cell intercalation before gastrulation. Nature 449 1049-1052... 

Ciruna, B.G., Schwartz, L., Harpal, K., Yamaguchi, T.P., Rossant, J. 1997. Chimeric analysis of fibroblast growth factor receptor-1 (Fgfrl) function a role for FGFR1 in morphogenetic movement through the primitive streak. Development 124, 2829-2841. 

Streit, A., Lee, K.J., Woo, I., Roberts, C., Jessell, T.M., Stern, C.D. 1998. Chordin regulates primitive streak development and the stability of induced neural cells, but is not sufficient for neural induction in the chick embryo. Development 125, 507-519. 

Perea-Gomez, A., Shawlot, W., Sasaki, H., Behringer, R.R., Ang, S.L. 1999. HNF3/J and Liml interact in the visceral endoderm to regulate primitive streak formation and anterior-posterior polarity in the mouse embryo. Development 126, 4499 1511. 

Shawlot, W., Wakamiya, M., Kwan, M.K., Kania, A., Jessell, T.M., Behringer, R.R. 1999. Liml is required in both primitive streak-derived tissues and visceral endoderm for head formation in the mouse. Development 126, 4925 1932. 

Three major types of craniofacial malformations were induced in hamsters upon oral adminstration of Veratrum alkaloids during the primitive streak/neural plate development phase which is on the eighth day of the hamsters 16 day gestation period [42]. These primary malformations include exencephaly. Fig. (5), which is a fully-exposed... 

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