Tag: structure of male and female reproductive structures

Endothecium is defined as the lining of the inner cavity of the anther. It is present as a middle layer. 

If chromosomes of megaspore mother cell are 10; it ensures that the diploid number is 10. 2n = 10. Therefore, n = 5. Aleurone layer will be triploid in nature. Thus, the number of chromosomes in aleurone layer = 15.

The pollen tube ultimately enters an ovule through the micropyle and penetrates one of the sterile cells on either side of the egg ( synergids). These synergids begin to degenerate immediately after pollination. 
Synergids are haploid in nature. Thus, if root cell has 2n = 42, synergids will have n = 21.

The hilum is the point of attachment of funicle with the chalazal end. It is the point where ovule attaches to the base. It is generally present as an eye of the seed as it is present as a scar.

The ovules where micropyle come to lie close to the funiculus due to unilateral growth of the ovule are called anatropous. This is the most common type of ovule in angiosperms where the curvature of the ovule also affects the nucellus so that the later becomes horse shoe-shaped. The ovule is called amphitropous.

When funicle lies at right angle to body of ovule and micropyle, the ovule is called hemianatropous or body of ovule has rotated by $90^{o}$.

The nucellus is a part of the inner structure of the ovule, forming a layer of diploid (sporophytic) cells inside the integuments. It is structurally and functionally equivalent to the megasporangium. In some plants, the diploid tissue of the nucellus gives rise to a seed through a mechanism of asexual reproduction called nucellar embryony.

Synergid is one of two small, short-lived nuclei lying near the egg in the mature embryo sac of a flowering plant. The synergids are part of the egg apparatus and are thought to help the pollen nucleus reach the egg cell for fertilization.