Histology USMLE Step 1 Practice Question
A 28-year-old male presents with a 10-year history of chronic heartburn and regurgitation unresponsive to lifestyle modification. Upper endoscopy reveals salmon-pink discoloration of the distal esophagus extending 6 cm above the gastroesophageal junction. Biopsy demonstrates replacement of the normal stratified squamous epithelium with simple columnar epithelium containing goblet cells. The patient is counseled about increased cancer risk and started on high-dose proton pump inhibitor therapy. Which of the following embryologic germ layers is responsible for forming the esophageal epithelium that has been replaced in this patient?
Answer choices
- AEndodermCorrect answer
- BMesoderm
- CEctoderm
- DNeural crest cells
- ETrophoblast
- FEpiblast
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.