Reproduction and fertilisation
The organs of sexual
reproduction are the gonads , which are the ovaries in females and the testes in males. Females produce female gametes, (eggs); males produce male gametes, (sperm).
Fertilisation
When a female is born, each of her ovaries has hundreds of thousands of eggs, but they remain dormant until her first
menstrual cycle, which occurs during puberty. At this time, during adolescence, the
pituitary gland secretes hormones that stimulate the ovaries to produce female sex
hormones, including oestrogen, which helps the female develop into a sexually mature woman. Every 28 days or so from puberty until menopause, between one and three eggs, the size of the head of a pin, are released from the ovaries. A complex set of hormonal events trigger the release of eggs and send them on their way down the fallopian tubes towards the Uterus. This whole process takes about three minutes and is known as ovulation. Sexual reproduction is the fertilization of a female gamete by a male
gamete. Before ovulation, the cervix produces a special mucous for about 3 to 9 days. This mucous is as crucial to fertility as ovulation because without it, the male’s sperm cannot survive nor be transported inside the female to fertilize the eggs. When mucous is present, it nourishes and protects sperm allowing them to live for 3 to 5 days.
Reproduction
Human reproduction is much the same for all mammals. It is the hallmark of life – essential for the cycle of living things.
Conception refers to fertilisation of the female egg by the male sperm. When an egg is released from one of the ovaries at ovulation, between day 9 and day 16 of the menstrual cycle, it makes its way down the fallopian tube to the already prepared uterus. During intercourse, the male ejaculates; about one tenth of an ounce of semen is deposited into the vagina. Between 200 and 300 million sperm are in this small amount of semen. If a female and male have sexual
intercourse within several days of ovulation,
fertilization can occur. The sperm travels through the cervix into the upper part of the uterus and then into the fallopian tubes where the sperm meets the egg. If the
sperm manages to enter the egg, it becomes fertilised and a new life can begin. It takes only one sperm to fertilize the egg.
The development of a baby
About a week after the sperm has fertilized the egg, the egg has become a multicelled blastocyst, a pinhead-sized hollow ball with fluid inside, now present in the uterus. The
blastocyst burrows into
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