title: Evidence for specific feedback signals underlying pattern control during vertebrate embryogenesis.
abstract: Experiments are described in which sectors including dorsolateral mesoderm from early-neurula-stage amphibian embryos are grafted to the mid-ventral region of gastrula-stage hosts. The grafted tissue pursues an autonomous developmental sequence, though integrated into the host mesodermal mantle, so that such embryos develop a ventral strip of ectopic somite tissue, occasionally with a pronephric formation at one side. When the proportions in which mesodermal tissue has been assigned to the four basic territories of the host's mediolateral pattern are assayed, a significant deficit in somite is characteristically found, though the phenomenon is variable in magnitude. It seems that the size of the host's pronephric territory may be diminished in a similar way, if an earlier differentiating ectopic pronephros is already joined to the system. These phenomena are discussed in relation to theories of biological pattern formation.
mesh_terms: D000558:Ambystoma mexicanum; D000818:Animals; D002452:Cell Count; D004625:Embryo, Nonmammalian / Q000502:physiology*; D005246:Feedback; D005775:Gastrula / Q000166:cytology; D007668:Kidney / Q000196:embryology; D008648:Mesoderm / Q000166:cytology; D009024:Morphogenesis; D014982:Xenopus laevis