Figure 2

Expression of bone morphogenetic protein-4 (BMP-4) in adrenal cortical cells at developmental stages S23 (B), S26 (F), S30 (J), and S35 (N). Adjacent sections were labelled for steroidogenic factor-1 (SF-1) (A,E,I,M), Phox2B (C,G,K,O) and tyrosine hydroxylase (TH) mRNA (D,H,L,P). The positions of the adrenal cortical anlagen (ac) or the adrenal gland (ag) are marked. (A-D) At S23, the TH/Phox2B-positive chromaffin progenitors are located outside, but closely attached to the adrenal cortical anlage. (E-H) At S26 they have started to invade the adrenal cortical anlage. (I-L) At S30 both cortical and TH-positive chromaffin cells are completely intermingled. da, dorsal aorta; sg, sympathetic ganglion. Bar: 100 μm.