(a) Amniocentesis : Amniocentesis is a toast on the fetus carried out during pregnancy to check for and to detect chrom-osomal abnormalities and other defects or disorder in the fetus. It can also be used for sex determination. It is carried out by testing a sample of amniotic fluid from the uterus of pregnant woman.
(b) Development of male gametophyte in angiosperms plants: Microspore or the pollen grains represents the initial cell of male gametophyte. During germination, the cytoplasm of the pollen grain comes out in the form of a tube like structure called pollen tube through the germ pore.
The pollan tube carries the tube nucleus cytoplasm and generative cell. The pollen tube grows though the style towards the ovule due to some chemical stimulus inside the ovary. The generative cell of the pollen grain divides by mitosis and forms two haploid non motile gametes. Pollen tube consisting of the two male gametes and a degenerating tube nucleus represents the male gametophyte.
