(a) (i) Explain the development of male gametophyte in an angiosperm. (ii) Draw a labelled diagram of a three-celled male gametophyte.

Each microspore mother cell in sporogenous tissue undergoes meiosis , forming

microspores tetrad by the process called microsporogenesis , microspores form cluster of four cells called microspore tetrad , as the anther matures and dehydrates, each microspore undergo assymetric division to produce a vegetative cell and a generative cell.

At embryonic stage

Both LH and FSH attain a peak level in mid of menstrual cycle rapid secretion of

LH leading to maximum level is called LH surge , which induces rupture of graffian follicle and cause ovulation , ovulatory phase is followed by luteal phase during which remaining parts of graffian follicle transform as corpus luteum , it produces large amount of progesterone needed for maintaining endometrium , in absence of fertilization corpus luteum degenerates which causes disintegration of the endometrium leading to menstruation.