Thursday, December 25, 2008
source of picture:http://encarta.msn.com/media_461516399/egg_cell.html
To me, the egg cell is always a special cell. It is as if it carries all the future of a new organism in itself.
The egg cell is the biggest cell in the body. It can even be seen without the aid of a microscope. It contains so much yolk especially in those animals that develop outside of the female’s body. The sperm cell only contributes its nucleus during fertilization, but the egg cell contributes not only its nucleus but also its cytoplasm and everything in it including the organelles.
During the early stages of development after fertilization, the yolk in the egg cell’s cytoplasm is actually the only source of nutrition for the growing embryo.
By the way, since the mitochondria of a developing embryo only comes from the egg cell, one line of research has tried to follow our supposed to be "Eve" by following the mitochondrial DNA or "mitochondrial Eve" through the ages.