Epithelial and mesenchymal cell interactions with extracellular matrix material in vitro
Epidermal organogenesis (thyroid gland, salivary gland, feather, hair, skin, thymus gland, tooth, etc.) generally follows a basic rule; epithelium exhibits well-documented interdependence with adjacent mesenchyme for a specific path of development (Grobstein, 1967, for review). Koch (1967) demonstrated in rodent embryos that isolates of incisor epithelial and mesenchymal tissue, separated by a millipore filter, continued to develop. When homotypic tissues were placed in juxtaposition to the filter, no evidence of continued differentiation was observed. Isolated cervical loop tissues of tooth germs from mammalian embryos have been shown to develop into an entire tooth in vitro (Slavkin & Bavetta, 1968 a; Kollar & Baird, 1969). Our laboratory recently reported that isolated tissue preparations (Slavkin & Bavetta, 1968 a) or cell suspensions (Slavkin, Beierle & Bavetta, 1968) of epithelial and mesenchymal cells from the embryonic cervical loop, in recombination on the chick chorioallantoic membrane (CAM), reconstituted and developed into a tooth germ.