Essay on Human Fertilisation and Development

The nucleus in an oocyte is called the germinal vessicel, and the nucleolus is referred to as the germinal spot. Eggs are produced in the ovaries, oval-shaped organs in the groin that also generate sex hormones. At birth, a female's ovaries contain hundreds of thousands of undeveloped eggs, each surrounded by a group of cells to form a follicle, or sac; however, only about 360-480 follicles reach full maturity. During puberty the action of hormones causes several follicles to develop each month. Normally, just one follicle fully matures, rupturing and releasing an ovum through the ovary wall in a process called ovulation. The mature egg enters one of the paired fallopian tubes, where it may be fertilized by a sperm and move on to the uterus to develop into a fetus. The lining of the uterus, called the endometrium, prepares for pregnancy each month by thickening, but if fertilization does not take place, the endometrium is shed during menstruation.
The development of a human begins with fertilization, a process by which the spermatozoan from the male and the oocyte from the female unite to give rise to a new organism, the zygote. During sexual intercourse, a man releases approximately 300 million sperm into a woman's vagina, but only one of the sperm can fertilize the ovum. The successful sperm cell must enter the uterus, swim up the fallopian tube to meet the ovum, and then pass through a thick…