Germ Layer Derivatives

A medical student is studying the derivatives of the three primary germ layers. Which of the following structures is derived from the endoderm?

Which of the following structures is derived from the endoderm?

A newborn male presents with a midline sacral dimple noted at birth. On examination, there is a small pit with a tuft of hair above it. Ultrasound of the lumbosacral spine shows a normal spinal cord with no tethering or syrinx. The parents are anxious about neurological complications. What is the most appropriate next step in management?

A 28-year-old primigravida presents at 20 weeks gestation for routine ultrasound. The scan reveals a large cystic mass in the fetal neck with multiple septa, extending from the angle of the mandible to the clavicle. The mass does not enhance significantly on Doppler. Amniocentesis and karyotyping are normal. The obstetrician counsels the parents that this lesion arises from remnants of the second and third pharyngeal pouches. Which of the following structures is derived from the same germ layer as the epithelial lining of this cyst?

A 28-year-old primigravida at 18 weeks gestation undergoes routine ultrasound screening. A fetal anomaly is detected: the fetus has a large midline defect in the anterior abdominal wall with herniation of bowel loops and liver into the amniotic sac. The defect measures 8 cm and is not covered by peritoneum or skin. Based on the embryological origin of this defect, what is the most appropriate next step in management?