(Polygonum) – Development of the Female Gametophyte (= embryo sac)
The Polygonum-type of embryo sac development is the most common type. This information is additional information that will help more with lecture content than lab 😉
The pictures to follow are in the same orientation that the Lily ovules were (micropylar end at lower end). The picture below shows the first meiotic division of the megaspore mother cell.
The two resulting nuclei then undergo the second meiotic division to produce four megaspores. In the picture below you can see the four megaspores and the walls forming between them.
In the next picture you can see that three of the megaspores are disintegrating (designated DM). The remaining (functional) megaspore is indicated (M).
The megaspore undergoes its first mitotic division (the two resulting nuclei are indicated with arrows:
Things are beginning to get a little difficult to see…….this next slide shows the second mitosis resulting in four nuclei:
The picture below is of the mature embryo sac…..it is difficult to distinguish the cells very well. So you see even though most plants have this type of embryo sac development it is much easier to see in the lily-type.
