Step 1: Structure of microsporangium.
A microsporangium has 4 wall layers: Epidermis, Endothecium, Middle layers, and Tapetum. These surround pollen mother cells.
Step 2: Understanding micropyle.
Micropyle is a small opening in the ovule, not a part of microsporangium.
Step 3: Conclusion.
Therefore, the part not belonging to microsporangium is Micropyle.