Detection of X-gal-positive signals in specific tissue organs of early developing UERB-LacZ embryos.

<p>A–D: X-gal signals are detected in the lateral plate mesoderm (lpm) and head fold structure (hf) of line #81 (A, B) and #96 (C, D) UREB-LacZ embryos at E8.5. E–G: At E9.5, the common regions containing X-gal-positive signals in all three lines of #28 (E), #81 (F) and #96 (G) are the anterior ridge of head (arrowhead), midbrain (mb), lateral plate mesoderm (lpm), mesonephric duct (md) and epidermis of embryonic bodies. Strong X-gal-positive signals are also detected in the branchial arches (ba) of line #81. H–M: Later at E10.5 (H–J) and E11.5 (K–M), prominent X-gal-positive signals are detected in the apical ectodermal ridge (AER, H, K, L) of limb buds and in olfactory pit (arrowhead, H–M). Although the expression levels are varied, selectively expression of <i>LacZ</i> in the branchial arches (ba) and its derivatives, including the mandibular (mdba1) and maxillary (mxba1) components of the first branchial arch, are consistently found in all three lines, (H–M), so as the selective expression of <i>LacZ</i> in the surrounding placodal tissues (arrow in H–M). A, C, E–H, J–M: side view; B, D, I: front view.