Group of specialized thickened nucellar cells between embryo sac and chalaza is

Options

A. Hypostase
B. Epistase
C. Tapetum
D. Endothelium.

Answer

To solve the question "Group of specialized thickened nucellar cells between embryo sac and chalaza is", we can follow these steps:

### Step 1: Understand the Components
- The question refers to the structure in the ovule, specifically between the embryo sac and the chalaza.
- The embryo sac is the female gametophyte, and the chalaza is the region of the ovule where the nucellus is attached.

### Step 2: Identify the Options
- The options provided are:
A. Hypostase
B. Epistase
C. Teptum
D. Endothelium

### Step 3: Analyze Each Option
- **Option A: Hypostase**
- Hypostase refers to the specialized thickened nucellar cells located between the embryo sac and the chalaza. This is the correct answer we are looking for.

- **Option B: Epistase**
- Epistase plays a role in guiding the pollen tube to the female gametophyte but is not located between the embryo sac and chalaza. Therefore, it is not the correct answer.

- **Option C: Teptum**
- Teptum is found in the anther and is associated with male gametophytes, making it irrelevant to this question about the female reproductive system.

- **Option D: Endothelium**
- Endothelium refers to the layer of cells lining the ovule but does not specifically refer to the thickened nucellar cells between the embryo sac and chalaza.

### Step 4: Conclusion
- After analyzing all options, we conclude that the correct answer is **Option A: Hypostase**.

### Final Answer
The group of specialized thickened nucellar cells between the embryo sac and chalaza is called **Hypostase**.

---