Question

Name the cells found in chalazal end of embryo sac

Answer 1

The megaspore divides three times to produce the embryo sac, which is the female gametophyte and will produce female gametes – the eggs. Megaspore undergoes mitosis for three times and forms 8 nucleate embryo sac.

Let us discuss in detail:

Megaspore mother cell (MMC) undergoes meiotic division to produce 4 megaspores. Out of these, 3 degenerates and one functional megaspore develops into theembryo sac.

This kind of development is called monosporic development. The nucleus of the functional megaspore divides mitotically to form 2 nuclei, which move towards the opposite ends, forming a 2-nucleate embryo sac.

Second and third mitotic divisions lead to the formation of 4-nucleate and 8-nucleate embryo sacs respectively. After the 8-nucleate stage, the cell walls are laid down and the typical female gametophyte (embryo sac) gets organized.

Six of the 8-nuclei get surrounded by the cell wall and the remaining two, called polar nuclei, are situated below the egg apparatus in the large central cell.

Three of the six cells are placed at themicropylar end and constitute the egg apparatus (2 synergids + 1 egg cell).

The synergids have special thickenings at the micropylar end. These are together called the filiform apparatus.

It helps in leading the pollen tubes into the synergids. Three cells are at the chalazal end, and are called antipodal cells.

A typical angiosperm female gametophyte is 7-celled and 8-nucleated at maturity

Answer 2

The cells found in the chalazal end of embryo sac are Antipodal cells.

These cells are three in number and are found in the opposite end of the ovule.

These antipodals are the nutritional cells of embryo sac.

They provide nutrients to the embryo sac and help in the growth and development of the embryo sac.