Early embryonic specification of vertebrate cranial placodes

摘要: Cranial placodes contribute to many sensory organs and ganglia of the vertebrate head. The olfactory, otic, lateral line form receptor cells neurons nose, ear, system; lens placode develops into eye; epibranchial, profundal, trigeminal cranial nerve ganglia; adenohypophyseal gives rise anterior pituitary, a major endocrine control organ. Despite these differences in fate, all are now known originate from common precursor, preplacodal ectoderm (PPE). latter is horseshoe-shaped domain surrounding neural plate crest defined by expression transcription factor Six1, its cofactor Eya1, other members Six Eya families. Studies zebrafish, Xenopus, chick reveal that PPE specified together with ectodermal territories (epidermis, crest, plate) during early embryogenesis. During gastrulation, domains ventrally (e.g., Dlx3/Dlx5, GATA2/GATA3, AP2, Msx1, FoxI1, Vent1/Vent2) dorsally Zic1, Sox3, Geminin) restricted factors established response gradient BMP help define non-neural competence territories, respectively. At stages, then induced territory signals adjacent mesoderm including FGF, inhibitors, Wnt inhibitors. Subsequently, more localized signaling centers induce various within PPE, which specify multiplacodal areas ultimately individual placodes. For further resources related this article, please visit WIREs website. Conflict interest: author has declared no conflicts interest for article.