Development of cranial nerves in the chick embryo with special reference to the alterations of cardiac branches after ablation of the cardiac neural crest.
Development of cranial nerve branches in the cardiac region was observed in whole-mount specimens which were stained with a monoclonal antibody, E/C8, after the ablation of the cardiac neural crest. In early embryos, nerve trunks of IX and X were lacking or only poorly developed, while the early development of pharyngeal branch primordia was normal. In day 5 embryos, the nerve trunks of IX-X were present in all the embryos, however; extensive communication was observed between X and XII. On day 6 and later, the spiral pattern of superior cardiac branches was disturbed, as were the blood vessels. Furthermore, the distal branches of XII passed within the superficial layer of cardiac outflow mesenchyme. Vagal branches passed within the deeper layer. There was no apparent change in the development of the sinal branch. Using quail--chick chimeras, it was found that the cardiac neural crest cells formed the Schwann cells of XII, and that they were also associated with the hypobranchial muscle primordium, suggesting that the absence of the cardiac neural crest not only disturbs the development of the cardiac outflow septation, but also affects the normal morphogenesis of the hypobranchial musculature and its innervation. Embryologically, the tongue is located close to the cardiac outflow tract, which is the migration pathway of the cardiac neural crest-derived cells.
Kuratani
S C
SC
Department of Anatomy, Medical College of Georgia, Augusta 30912-2000.
Miyagawa-Tomita
S
S
Kirby
M L
ML
D000818:Animals; D002642:Chick Embryo / Q000502:physiology*; D003391:Cranial Nerves / Q000196:embryology*; D005314:Embryonic and Fetal Development; D005930:Glossopharyngeal Nerve / Q000196:embryology; D006329:Heart Conduction System / Q000196:embryology*; D007002:Hypoglossal Nerve / Q000196:embryology; D009432:Neural Crest / Q000502:physiology*; D014630:Vagus Nerve / Q000196:embryology