## **Core Concept**
Intrinsic factor is a glycoprotein produced in the stomach that plays a crucial role in the absorption of vitamin B12. It binds to vitamin B12 from food and facilitates its absorption in the ileum. The production of intrinsic factor is essential for preventing vitamin B12 deficiency.

## **Why the Correct Answer is Right**
The correct answer, **parietal cells**, are responsible for secreting intrinsic factor. Parietal cells, also known as oxyntic cells, are found in the gastric glands of the stomach lining. They secrete hydrochloric acid and intrinsic factor. The intrinsic factor-vitamin B12 complex is then absorbed in the terminal ileum through a specific receptor-mediated process.

## **Why Each Wrong Option is Incorrect**
* **Option A:** Chief cells primarily secrete pepsinogen, which is converted to pepsin in the acidic environment of the stomach. While they are involved in digestion, they do not produce intrinsic factor.
* **Option B:** Enterochromaffin-like cells (ECL cells) release histamine, which stimulates parietal cells to secrete hydrochloric acid. They are not responsible for intrinsic factor production.
* **Option C:** Mucous neck cells produce mucin, which helps protect the stomach lining. They do not produce intrinsic factor.

## **Clinical Pearl / High-Yield Fact**
A key clinical correlation is that patients with **pernicious anemia**, an autoimmune condition where the body produces antibodies against intrinsic factor or parietal cells, cannot absorb vitamin B12 and require lifelong vitamin B12 injections or oral supplements.

## **Correct Answer:** . Parietal cells