Fig. 8 The development of regional character in LS neural segments bordered by T paraxial mesoderm. (Top left) A schematic of the surgery. Paraxial mesoderm on one side of the anterior LS neural tube of a stage 13 chick embryo was replaced with stage 11-13 anterior T paraxial mesoderm from a chick or quail embryo. (A) Ventral view of the LS cord from one stage 29 embryo. Hoxd10 expression is high in LS neural tissue adjacent to the transplant region, although, the lateral strip of high Hoxd10-expressing cells is reduced. (B-D) Sections through the anterior LS region of a stage 29 embryo. (B) The experimental side (arrow) shows lower Hoxd10 expression in the mesoderm than the control side. In neural tissue, Hoxd10 expression (B) as well as Isl1/2 (C) and Lim1/2 (D) protein patterns are normal on the experimental side with the exception of a decrease in motor column size. (E-G) Sections through the anterior LS region in a stage 29 quail/chick chimera. The experimental side is marked with an arrow. Hoxd10 expression is equivalently high on both sides of the LS cord (E), despite the fact that the control side is bordered by chick myotomal cells of LS origin (F) and the experimental side is bordered by quail myotomal cells of T origin (G). Bars, (A-E) 250 µm; (F-G) 25 µm.
