Fig. 2. Whole-mount in situ analysis of XHRT1, esr9, esr10, Xhairy1 and Xhairy2b in comparison with X-Delta-1 and X-Serrate-2 in the pronephros region (arrowheads) of late tailbud to tadpole stage embryos. Nieuwkoop-Faber stages are indicated. (A) At stage 25, XHRT1 is expressed in the most dorsoanterior portion of the pronephros anlagen. (B) Transversal section of the embryo shown in A at the level indicated. (C-P) Expression of XHRT1, esr9, esr10, Xhairy1, Xhairy2b, X-Delta-1 and X-Serrate-2 in stage 28 embryos. (A,C,E,G,I,K,M,O) Whole embryos, lateral views; (B,D,F,H,J,L,N,P) transversal sections of the corresponding embryos at the level indicated. Note that esr9 and esr10 staining appears slightly ventral compared with XHRT1. While X-Delta-1 expression is restricted to a band just below XHRT1, Serrate2 expression is broader. (Q,R) Double labeling of XHRT1 and X-Delta-1 or Xhairy2b. (S,T) At stage 35, Xhairy2b is co-expressed with X-Serrate-1 in the proximal and distal tubules. dt, distal tubules; pn, pronephros; pt, proximal tubules; m, medial intermediate mesodermal layer.