title: Developmental anomalies of the lower face and the hyoid cartilage due to partial elimination of the posterior mesencephalic and anterior rhombencephalic neural crest in chick embryos.
abstract: In an effort to verify the supposition that a normal development of the lower face and the hyoid apparatus is dependent on the availability of a sufficient number of cells derived from the posterior mesencephalic and anterior rhombencephalic parts of the neural crest, in a total of 52 six-somite stage chick embryos (about 26 hours of incubation) these parts of the neural crest were partially eliminated by tangential micro-laser irradiation. Among the 17 irradiated embryos sacrificed after 24 hours, several ones showed an underdevelopment of the mesenchyme in the ventral part of the first branchial arch; in 2 of these cases, additionally the second branchial arch was underdeveloped. At the age of 7-8 days, 4 out of 15 surviving embryos showed an underdevelopment of the lower beak and a reduction in size of Meckel's cartilage; in 3 of these cases, in addition, a median cleft in the lower beak and/or reduction or absence of the hyoid cartilage were observed. From these observations the conclusion is drawn that for a normal development and growth of the mandibular part of the face and the hyoid cartilage sufficient numbers of posterior mesencephalic and anterior rhombencephalic neural crest cells are indispensable, indeed.
mesh_terms: D000015:Abnormalities, Multiple / Q000196:embryology*; D000818:Animals; D001921:Brain / Q000196:embryology*; D002356:Cartilage / Q000002:abnormalities*; D002642:Chick Embryo; D005145:Face / Q000002:abnormalities*; D006928:Hyoid Bone / Q000002:abnormalities*; D008636:Mesencephalon / Q000196:embryology*; D009432:Neural Crest / Q000033:anatomy & histology / Q000502:physiology*; D013997:Time Factors