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 Human reproduction may seem basic - sperm penetrates egg to fertilize - but it is actually a very complex and surprisingly inefficient process. The health and fertility of both partners is involved and problems can arise at any point along the way. Here's an overview of the different phases of the reproductive process. For more information and to see an animation depicting what goes on in the body during reproduction, see http://www.seronocycle.com/. Producing the Egg and the Sperm Egg Women are born with about 400,000 eggs stored in two small organs called the ovaries. Eggs develop and mature inside follicles, which are tiny fluid-filled sacs in each ovary. Midway through the menstrual cycle, during ovulation, one egg is released from a follicle. Sperm Sperm is produced by the testes (or testicles) - glands located in the scrotum. As sperm are produced, they pass through the coiled channels of the epididymis, an organ that stores and nourishes sperm. When completely mature, sperm move through the vas deferens to the seminal vesicles. The entire process takes about 72 days. However, it is an ongoing process, and sperm are being manufactured all the time. Fertilization  After the egg travels along one of the fallopian tubes toward the uterus, it is ready for fertilization. When a man ejaculates (releases fluid from his penis during sexual stimulation), sperm combine with a thick fluid from the prostate gland to create semen. The fluid (or ejaculate) is deposited into the woman's vagina during intercourse. Sperm swim into the cervical mucus, then into the uterus and along the fallopian tube, where the egg and sperm unite. If a sperm penetrates the egg, fertilization occurs. The best time for fertilization and pregnancy A woman's fertile time is around midcycle when ovulation occurs - on or about the 14th day after the first day of the period. Unlike the rest of the monthly cycle, this is when cervical mucus is receptive to sperm. The egg can be fertilized for about 24 to 48 hours after it is released from the follicle. Sperm can live 48 to 72 hours within the female reproductive tract, retaining the ability to fertilize an egg. Implantation The fertilized egg travels back through the fallopian tube toward the uterus. The uterus is the muscular organ where a fertilized egg, or embryo, attaches and develops. It is about the size and shape of a pear and is lined with rich and nourishing mucous membrane called the endometrium. Once inside the uterus, the fertilized egg implants itself into the lining of the uterus, where it will gain nourishment as it grows. If fertilization does not occur, the egg passes through the uterus. The uterus will then break down and shed its lining several days later, and the next menstrual period begins.
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| Female  A women's monthly menstrual cycle drives the reproductive process. The cycle occurs in three phases:
The cycle is controlled by several hormones:
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Age-associated Concerns
It is important to remember that age is not an absolute barrier to pregnancy. However, female fertility does decrease with age.
This decline seems to be a direct result of the age-related decline in the number of healthy eggs in a woman's ovaries. A woman is born with all the eggs she will ever have. The quantity of eggs starts to diminish in childhood and continues into adulthood. Ovulation contributes to the decrease, but the majority of eggs are slowly absorbed by the body. By the fifth or sixth decade of life, most women will have depleted the egg supply they were born with. Ovarian failure occurs when a woman's follicles and eggs are depleted and when the production of the hormones estrogen and progesterone ceases.
Other factors can also affect reproductive functioning in older women. These include frequency of intercourse, which may decline with increasing age and the duration of a couple's relationship; irregular ovulation, which occurs as a woman's hormone levels change with age; and luteal phase deficiencies, which occur when too little progesterone is produced to maintain a sufficient uterine lining for a fertilized egg to implant into.
Services | Healthplans | Home | Office Staff | Directions Birchwood Women's Health, P.S. |
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| Male  The development of normal, mature sperm is the key to male fertility. Sperm production is primarily regulated by two hormones:
FSH is responsible for stimulating sperm production in the testicles. LH stimulates the production of testosterone, the hormone that helps maintain male sexual characteristics. Under the influence of testosterone and other hormones, immature sperm cells develop through several stages and eventually become mature sperm cells, called spermatozoa. Spermatozoa then pass through the epididymis, where, after 18 to 24 hours, they gain motility, or movement. Finally, mature sperm move through the vas deferens and are stored in the seminal vesicles until ejaculation. The complete process takes about 72 days. When a man ejaculates (or expels the fluid from his penis), sperm from the seminal vesicles combine with a thick fluid from the prostate and other glands to create semen. This fluid can be deposited into a woman's vagina, where it travels through the cervix and uterus to fertilize an egg. Age-associated Concerns Age affects a man's reproductive potential. The major causes for this are the quality of the ejaculate and the frequency of intercourse. For some men, advancing age is associated with declining testosterone levels, decreased sexual interest, and reduced sexual activity. Sperm motility can also decline with age. However, men continually produce sperm, so the decline in fertility in men isn't as pronounced as it is in women. A Delicate Balance Any change in the complicated sequence of events in the male or female reproductive cycle can disrupt ovulation, conception, or pregnancy, possibly resulting in infertility.
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