A 13-year-old boy is brought to the clinic due to progressive difficulty with breathing, hoarseness, and dysphagia.  The symptoms began insidiously 6 months ago but have rapidly become worse in the last 4 weeks.  The patient has no associated skin rash, pharyngeal pain, fever, weight loss, or loss of appetite.  Medical history is unremarkable and the patient takes no medications.  He is up to date on scheduled vaccinations.  The patient’s parents and siblings have no history of significant health problems.  Vital signs are normal, and he is at 70th percentile for height and weight.  Oropharyngeal examination reveals a large, red lingual mass.  The patient subsequently undergoes excision of the mass; histopathologic preparation of the recovered tissue is shown in the image below.

Failure of which of the following embryologic processes is most likely responsible for this patient’s lesion?

A newborn is taken to the neonatal intensive care unit after delivery due to respiratory distress.  The neonate was born full-term, and there were no significant complications during pregnancy or delivery.  Once the patient is stabilized, a detailed physical examination is performed.  The neonate has an underdeveloped mandible and hypoplastic zygomatic bones.  Genetic testing confirms a gene mutation that results in abnormal development of the first and second pharyngeal arches.  Which of the following structures is also likely abnormal in this patient?

A 1-week-old boy is brought to the emergency department with poor feeding, lethargy, and unusual “muscle movements” involving the left thumb and hand over the last 2 days.  The patient’s mother had appropriate prenatal care, a normal pregnancy, and took no medications other than prenatal vitamins.  The infant’s vital signs are normal, but unusual flexion of the left wrist and thumb and extension of the fingers are observed with cuff blood pressure measurement.  Physical examination reveals a hypoplastic mandible, low-set ears, bifid uvula, and cleft palate.  A chest x-ray reveals decreased soft-tissue attenuation in the right anterior mediastinum.  These findings most likely suggest impaired development of which of the following embryonic structures?