A 4-year-old boy presents with recurrent lower respiratory tract infections and a chronic productive cough with foul-smelling sputum. Vital signs show temperature 38.2°C, heart rate 102/min, respiratory rate 26/min, and oxygen saturation 94% on room air. High-resolution CT chest reveals situs inversus totalis, bronchiectasis, and centrally located liver. Nasal endoscopy demonstrates immotile cilia. Immunoglobulin levels are normal. Which embryologic process is disrupted in this condition?
- A)Endoderm-derived respiratory diverticulum budding
- B)Nodal signaling and establishment of left-right asymmetryGABARITO
- C)Neural crest cell migration to cardiac outflow tract
- D)Lateral plate mesoderm folding and body cavity formation
- E)Mesenchymal condensation in limb bud development
Explicação
Primary ciliary dyskinesia (PCD) involves defective nodal signaling during early embryogenesis. The nodal protein, normally expressed in the embryonic node, is essential for establishing left-right asymmetry. When nodal function is impaired, situs inversus tot... Ver explicação completa e trilha adaptativa →