TOPICS: Fibroblast growth factor (FGF), wnt-7, homeobox (Hox), sonic hedgehog (SHH), limb development, limb elongation, dorsal development, ventral development, transcription factors, apical ectodermal ridge (AER), polydactyly, syndactyly, holoprosencephaly, body patterning, limb orientation, prosencephalon (forebrain), mesencephalon (midbrain), rhombencephalon (hindbrain), spinal cord, telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon, neural tube, spectrum of midline defects, blastocyst, morula, fertilization, blastomere, oocyte, implantation, uterine epithelium, trophoblast cells, inner cell mass, bilaminar disc formation, outer cell mass (trophoblast), epiblast, yolk sac, syncytiotrophoblast, hypoblast, cytotrophoblast, gastrulation, primitive streak, endoderm formation, mesoderm formation, ectoderm formation, amniotic sac enlargement, cardiac development, neural tube formation, embryo, amniotic cavity, umbilical cord formation, organogenesis, chorion, umbilical cord, amnion, placenta, fetus, inner layer of chorionic villi, outer layer of chorionic villi, ovary, early fetal development