Figure 5.

Digit Formation in the Human Embryo at CS20 and 23

All sections were cut across the dorsal ventral axis with respect to the hand plate. In situ analysis of mRNA expression for BMP4 (A, D, G, J, M, and P), SHH (B, E, H, K, N, and Q), and PTCH1 (C, F, I, L, O, and R). (A)–(I) show CS20 stages; (J)–(R) show CS23 stages. The following abbreviations are used: Iz, interdigital zone; Di, digit; Te, tendon; Ca, cartilage; Jc, joint capsule; and Per, pericardium; and Dct, dense connective tissue. The scale bar for (A)–(C) and that for (J)–(L) represent 1000 μm, for (D)–(F) and (M)–(O), 500 μm, and for (G)–(I) and (P)–(R), 50 μm. Arrows indicate areas of strong expression.