Difference Between Hilum and Micropyle

The key difference between hilum and micropyle is that helium is an elliptical scar on the seed, which marks the point of attachment to its seed vessel, while micropyle is a small pore from which the pollen tube enters the ovary prior to fertilization.

A seed is a fertilized ovule of a seed plant. There are two types of seed plants: angiosperms and gymnosperms. In angiosperms, the seed lies within a fruit, while in gymnosperms, seeds are naked. After formation, a seed germinates and produces a new plant. A seed has several parts. Testa is the seed coat that protects the embryo. Hilum and micropyle are two characteristic markers of the seed. In fact, hilum is the scar on the seed coat that shows the location at which the ovule and the ovary wall attach to each other while micropyle is a small pore which shows the point from which the pollen tube entered the ovary during fertilization.

CONTENTS

1. Overview and Key Difference
2. What is Hilum 
3. What is Micropyle
4. Similarities Between Hilum and Micropyle
5. Side by Side Comparison – Hilum vs Micropyle in Tabular Form
6. Summary

What is Hilum?

The hilum is a scar on the seed. It is the point from which the ovule and ovary connect to each other during the fertilization. Hilum controls the relationship between the external environment and the embryo. Moreover, the cutin in the hilum regulates the permeability of the seeds. Especially, at the final stage of seed formation, hilum controls the water content of the seed. Despite all positive factors, hilum provides a path for an invasion of pathogens in the seed.

What is Micropyle?

The micropyle is a small pore located at one end of the hilum of seeds. It is the point or pore from which the pollen tube enters the ovary during the fertilization process.

During seed germination, water enters the seed via micropyle. Similar to the hilum of the seed, micropyle also acts as a route for an invasion of pathogens in the seed.

What are the Similarities Between Hilum and Micropyle?

• Hilum and micropyle are two markers located in the seed coat.
• Both are routes for the invasion of pathogens in the seeds.
• Also, both hilum and micropyle facilitate water absorption into the seed.

What is the Difference Between Hilum and Micropyle?

Hilum is a scar on a seed that shows the connection between the ovule and ovary while micropyle is a pore that shows the point from which the pollen tube entered the ovary during fertilization. So, this is the key difference between hilum and micropyle. Structurally, hilum is a larger area of a seed while micropyle is a small pore. Therefore, we can consider this too as a difference between hilum and micropyle.

Moreover, the major function of the hilum is to fix the ovule to the ovary wall. Whereas, the major function of the micropyle is to facilitate the entry of pollen into the ovary. Functionally, this is a difference between hilum and micropyle. Besides, when considering the regulation of water absorption, hilum controls the water absorption during the final stages of seed formation while micropyle controls the water absorption during the seed germination.

Summary – Hilum vs Micropyle

Hilum and micropyle are two characteristic markers located on the seed coat. Hilum shows the attachment site of the ovule to the ovary wall. On the other hand, micropyle shows the point from which the pollen tube entered the ovary during the fertilization. Both hilum and micropyle are important for the seed. At the same time, they act as a route for the invasion of pathogens in the seed too. Thus, this is the summary of the difference between hilum and micropyle.

Reference:

1. “Hilum (Biology).” Wikipedia, Wikimedia Foundation, 13 Mar. 2017, Available here.
2. “micropyle.”. “Micropyle.” A Dictionary of Biology, Encyclopedia.com, 2019, Available here.

Image Courtesy:

1. “41533” (CC0) via Pixabay