What is the Difference Between Hilum and Micropyle?

The hilum and micropyle are two distinctive markers found on the seed coat, which is a multi-layered tissue developed from the integuments surrounding the embryo sac. They serve different functions and have distinct characteristics:

• Hilum: This is an elliptical scar on seeds that marks the point of contact and attachment of the funicle (a thread-like structure that connects the ovule to the placenta). The hilum controls water absorption during the final stages of seed formation.
• Micropyle: This is a small opening of the hilum through which the pollen tube passes before fertilization. The micropyle serves as the path for invasion of pathogens in seeds and regulates water absorption in some species. At the time of germination, water passes into the seed through the micropyle.

In summary, the hilum is an elliptical scar on seeds that marks the point of attachment of the funicle, while the micropyle is a small opening of the hilum through which the pollen tube passes before fertilization. Both structures play crucial roles in seed development and function.

Comparative Table: Hilum vs Micropyle

Here is a table highlighting the differences between the hilum and micropyle:

The hilum is a scar on the seed coat that marks the point of attachment of the ovule to the ovary wall. On the other hand, the micropyle is an opening on the seed coat that allows water to enter during germination and serves as a path for the invasion of pathogens.