An 18-year-old male comes to your primary care clinic complaining of pain near the breastbone for the last three days. It is a sharp pain that gets worse when he presses on the bone, moves sideways, and when he takes a deep breath, coughs, or sneezes. He can’t even laugh comfortably. The pain has no relationship with meals. His grandmother gave him a nitroglycerin tablet, but it did not relieve the pain. He also took some over-the-counter antacids without any relief. On further questioning, he reveals that he has been doing lots of exercises as part of his athletic training, including lifting heavy weights in the gym to develop a “six-pack” physique. Vital signs: Temperature: 98.8 °F Heart rate: 67 beats/min Blood pressure: 110/78 mm Hg Respirations: 15 breaths/min Oxygen saturation: 98% on room air Physical examination: Significant for tenderness over the sternum and right-sided ribs. ECG: Normal. Laboratory tests: Normal troponin levels. What is the next step in the management of this patient?

A 27-year-old man presents to the emergency department with complaints of chest pain and hemoptysis. He reports a history of chronic sinusitis and recurrent pneumonias requiring multiple hospitalizations. He also mentions infertility in his family history, noting that he and his wife have been unable to conceive. During the physical examination, you notice heart sounds on the right side of the chest, and he confirms that he has situs inversus. Pulmonary function tests (PFTs) reveal a decreased FEV1/FVC ratio, consistent with obstructive lung disease. A CT scan of the chest shows dilated bronchioles with a signet-ring appearance and situs inversus. Which of the following embryonic processes is most likely defective in this patient?