MEGASPOROGENESIS

These is a processes of formation of megaspore from diploid megaspore mother cell theough meiosis is called as megasporogenesis .

As already known the young ovule is composed of homogenous mass of tissue called nucellus.

In the hypodermal region of nucellus to words the my cropylarend  one cell becomes enlarge and filled with dense cytoplasm containing a prominent nucellus . Such a cell called primary archesporial cell .

The archesporial cell divides transversely into outer primary parietal cell and inner primary sporogenous cell .

Primary parietal cell may divide one or more time but some time may remains undivided .

The sporogenous cell directly function as single diploid megaspore arranged in a linear tetrad mother cell or mega spore mother cell .

The megaspore mother cell undergoes meiosis to form four haploid megaspores arranged in a linear tetrad .

Out of these 4 megaspore in a the linear tetrad the upper three degenerate and the lower most remains functional towards chalazal end .