Fig. 8. Model of dermal condensation formation in dorsal chick embryo skin. The chronological events from dense dermis to stabilized dermal condensation require a molecular dialogue both inter- and intra-tissular in the skin (see the text). Note that the placodes are larger and earlier than the dermal condensations (Dhouailly, 1984). This model took into account only the BMP genes, as well as a few other important genes among those expressed in embryonic skin.