Ubisch bodies are secreted by

Options

A. Tapetum
B. Exine
C. Microspore mother cells
D. Endothecium

Explanation

### Step-by-Step Solution:

1. **Understanding the Context**: The question asks about Ubisch bodies and their origin. Ubisch bodies are associated with pollen grains, which are produced by the male reproductive part of flowering plants known as the anther.

2. **Identifying the Structure of Anther**: The anther consists of several layers, including the outermost layer (epidermis), connective tissue, endothelium, sporogenous tissue, and the innermost layer known as the tapetum.

3. **Role of Tapetum**: The tapetum is crucial as it provides nourishment to the developing pollen grains. It is made up of glandular cells that play a significant role in the formation of pollen.

4. **Secretion of Ubisch Bodies**: Ubisch bodies are secreted by the tapetum. These bodies are involved in the formation of the outer layer of pollen grains, which is known for its resistance to enzymatic degradation.

5. **Function of Ubisch Bodies**: The Ubisch bodies contain sporopollenin, a tough organic substance that contributes to the structural integrity of the pollen grain. This makes pollen grains resistant to various environmental factors and enzymatic actions.

6. **Conclusion**: Therefore, the correct answer to the question is that Ubisch bodies are secreted by the tapetum.

### Final Answer:
Ubisch bodies are secreted by the tapetum.

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