**Core Concept**
The Graafian follicle is a mature follicle in the ovary containing a large oocyte. Surrounding the oocyte are specialized cells that play a crucial role in its development and maturation. These cells are essential for maintaining the oocyte's health and preparing it for ovulation.

**Why the Correct Answer is Right**
The cells surrounding the oocyte in the Graafian follicle are called cumulus oophorus cells. These cells are a type of somatic cell that forms a layer around the oocyte, providing it with essential nutrients and support. The cumulus oophorus cells are connected to the oocyte through gap junctions, allowing for the exchange of ions and small molecules. This close association between the cumulus oophorus cells and the oocyte is critical for the oocyte's development and maturation.

**Why Each Wrong Option is Incorrect**
* **Option A:** Discus proligerus refers to the layer of cells beneath the cumulus oophorus, not the cells surrounding the oocyte.
* **Option C:** Luteal cells are involved in the formation of the corpus luteum after ovulation, not in the Graafian follicle.
* **Option D:** Villus cells are found in the small intestine and are not related to the Graafian follicle or the oocyte.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that the cumulus oophorus cells play a critical role in maintaining the oocyte's health and preparing it for ovulation. Damage to these cells can lead to oocyte damage or failure to ovulate.

**✓ Correct Answer: B. Cumulus oophorus**