The vagus and recurrent laryngeal nerves in experimental congenital diaphragmatic hernia.
BACKGROUND
The etiology of the anatomic and functional abnormalities of the esophagus in infants surviving congenital diaphragmatic hernia (CDH) remains unclear. We showed previously that fetal rats with CDH have malformations of neural crest-derived structures. The aim of this study was to examine the anatomy of the vagus and the recurrent laryngeal nerves, both of neural crest origin, in rats with CDH.


METHODS
We used the nitrofen-induced CDH fetal rat model. Nine control fetuses from four dams and nine fetuses with CDH from seven dams were included in this study. Embryos were fixed in formalin and a thoracic block from the larynx to tracheal bifurcation was serially sectioned in the horizontal plane. One in every ten sections was stained with hematoxylin and eosin. The image was digitalized using biological software (TDR-3dbase). Vagus and recurrent laryngeal nerves, trachea, esophagus and the great vessels were examined. In order to obtain the three-dimensional reconstructions, 90-120 consecutive images were used.


RESULTS
In comparison with controls there were striking abnormalities of the vagus and the recurrent laryngeal nerves in fetuses with CDH: (1) absence of the left (2/9) or right (2/9) vagus nerves; (2) absence of the left (3/9) or right (3/9) recurrent laryngeal nerves; (3) marked hypoplasia of the trunk of the vagus (2/9); (4) deviations of their normal course and change of normal anatomical relationships into the mediastinum (2/9); and (5) abnormal branching of the lower portion of the vagus (1/9).


CONCLUSIONS
Rat fetuses with CDH have anomalies of the vagus and recurrent laryngeal nerves that support the concept of a neural crest involvement in the origin of this malformation. 3-D reconstructions allow a detailed analysis and provide a precise insight into the real anatomy. These observations may explain esophageal motility disorders in CDH.
Martínez
L
L
Department of Pediatric Surgery, Hospital Infantil Universitario La Paz, Paseo de la Castellana 261, 28046 Madrid, Spain.
González-Reyes
S
S
Burgos
E
E
Tovar
J A
JA
D000818:Animals; D005260:Female; D006540:Herbicides; D006548:Hernia, Diaphragmatic / Q000139:chemically induced / Q000473:pathology*; D065630:Hernias, Diaphragmatic, Congenital; D021621:Imaging, Three-Dimensional / Q000379:methods; D023421:Models, Animal; D009432:Neural Crest / Q000002:abnormalities; D010647:Phenyl Ethers; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012009:Recurrent Laryngeal Nerve / Q000002:abnormalities*; D014630:Vagus Nerve / Q000002:abnormalities*
D006540:Herbicides; D010647:Phenyl Ethers; C007350:nitrofen