The micropyle covers the upper surface of the egg and is not depressed.
At one end a cap-like portion of this forms a detachable operculum, in the middle of which is a minute opening, the micropyle.
This opening is called the “micropyle,” and allows the pollen tube to enter.
In some cases it is advisable to slice off the end of the egg with the micropyle and mount it microscopically.
If I have time I will have another look at pollen-tubes, as, from what you say, they ought to find their way to the micropyle.
On the upper end in some species they have a few short, vertical ridges, radiating from the micropyle.
The second type of micropyle is found in many Insecta, Teleostei, etc.
The pollen-tube does not penetrate the ovule through the micropyle but enters at the opposite end—the chalaza.
The function of the stalk and of the micropyle during the development of the ovum is undoubtedly a nutritive one.
The base of the nucellus is indicated by the chalaza ch, while the apex is at the micropyle m.