Paraxial mesoderm embryos

Trainor, P.A., Tan, S.S., Tam, P.P.L. 1994. Cranial paraxial mesoderm-regionalization of cell fate and impact on craniofacila development in mouse embryos. Development 120, 2925-2932. 

Jen WC, Wettstein D, Turner D, Chitnis A, Kintner C. (1997) The Notch ligand, X-Delta-2, mediates segmentation of the paraxial mesoderm in Xenopnis embryos. Development. 1997 124(6) 1169-1178. 

Trainor PA, Tam PPL (1995) Cranial paraxial mesoderm and neural crest cells of the mouse embryo co-distribution in the craniofacial mesenchyme but distinct segregation in branchial arches. Development 121 2569-2582. 

Here the host emhryo is operated in ovo, which is suitahle with ease only for embryos older than about 36 8 h incubation. As an example, the operation described here consists of a graft of presomitic mesoderm (segmental plate) with a quail embryo as the donor and a chick embryo as the host. An identical procedure can be followed to transplant paraxial mesoderm that has already formed somites, but it should be remembered that this is much easier when it... 

Fig. 1. A and D Ectopic transplantation of notochord (ect Not med asterisks) medially between neural tube and paraxial mesoderm A dorsal view, anterior to the top D cross section, dorsal to the top the axial level of the section is indicated in A. The operation has been performed at the level of the anterior segmental plate after 24h reincubation, the embryo was stained for the expression of the sclerotome marker Paxl (gray), the myotome marker MyoD (black), and the notochord—floor plate marker Shh (black). Note the ectopic notochord induced ectopic expression of Paxl and MyoD (arrowheads).

The manipulation described here results in an ectopic induction of the sclerotome, as shown by Dietrich et al. ((9) Fig. lA and ID), and floor plate, as shown by Goulding, Lumsden, and Grass (14), since the graft faces the dorsoventrally uncommitted neural plate and paraxial mesoderm. For this operation, the host embryos need to be at HH 9-10 and the site of operation is the open neural plate... 

Roll off the neural plate from the paraxial mesoderm as described in section 3.3.2.2.2, item 3, this time fully separating the neural plate from the paraxial mesoderm on the side of entry into the embryo. 

Make the anterior cut through the notochord at a position close to the somitic paraxial mesoderm. Then, ease the notochord between the cut and the node out of the embryo. 

Langeland, J.A., Tomsa, J.M., Jackman, W.R. and Kimmel, C.B. (1998) An amphioxus snail gene expression in paraxial mesoderm and neural plate suggests a conserved role in patterning the chordate embryo . Development Genes and Evolution, 208, 5G9-77. 

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