Reproductive Technologies

Megan Sobocinski, Kenny Marrs, Sharita Rude and John Wanot

Infertility and SubfertilityInfertility- The inability to conceive a child after

a year of unprotected intercourse

Subfertility- Individuals and couples that can conceive unaided, but may take longer than usual

As a woman ages, the incident of pregnancy-related problems rises

Men's age doesn't raise any risks

90% of cases can identify a physical cause

30%- primarily in the male

60%- primarily in the female

Infertility and Subfertility, cont'dA mutation or chromosomal aberration that impairs fertility in the male

20% of the 90% both partners have a medical condition that could contribute- irregular menstruation cycle and low sperm count.

1 in 6 couples have difficulty in conceiving or giving birth.

Differences in fertility problems between men and women

Male Infertility

Easier to detect but harder to treat than female infertility.

One in 25 men is infertile.

Oligospermia- producing fewer than the average 120 million sperm cells per milliliter.

In most cases it's genetic.

About a third of infertile men have deletions of the Y chromosome that remove the only copies of key genes whose products control spermatogenesis.

Male Infertility, cont'dMutations in genes that encodes

protein fertility hormones that regulate sperm development or motility.

Quality over quantity

Apoptosis (programmed cell death) selectively kills abnormally shaped sperm.

High percentage of abnormal shaped sperm often have cell surface molecules that indicate impaired apoptosis.Abnormally shaped sperm

Female Infertility

Can be caused by abnormalities in any part of the reproductive system.

Hormonal imbalance

Under active thyroid gland

Steroid-based drugs like cortisone

Abundant amount of prolactin in a non-pregnant woman

Fertility drugs stimulate ovulation but can cause woman to 'super-ovulate'

Female Infertility, cont'dCommon cause- blocked

uterine tubes

Infection- pelvic inflammatory disease

Excess tissues growing n the uterine lining that can include benign tumors like fibroid

Endometriosis- thickened lining that hormonally cues to menstruate, tissue bleeds causing cramps

Secretions that are hostile to sperm

Oocyte fails to release sperm-attracting biochemicals.

Infertility Tests

Urologist performs sperm test

Checks sperm count, motility and shape

Ejaculate containing up to 40% unusual forms is still considered normal

Many more than this can impair fertility

Genetic counselor may help in identifying the cause of male infertility- interpret the results of a PCR analysis of Y chromosome.

Females: Gynecologists that check to see if the structures of the reproductive system are present and functioning.

Assisted Reproductive Technologies

In 2001, 1% of approximately 4 million births in the United States were from ARTs (Assisted Reproductive Technologies).

ART births account for .04% of single births and 16% of multiple births.

Comparison of the success rates of the different ARTS

Donated Sperm- Intrauterine Insemination

Intrauterine Insemination is the oldest assisted reproductive technology.

Doctor places donated sperm into a woman's reproductive tract, typically the cervix or uterus.

First done in 1790, when sperm was donated by doctors and medical students.

Cost: Between 125 and 3000 dollars

Parents can choose sperm based on personal characteristics of donor.

Problems include late-onset genetic disorders.

A Donated Uterus- Surrogate Motherhood

Helpful when woman's uterus damaged or absent.

'Surrogate mother' can carry child by being inseminated by man's sperm. When child is born, it is given to the couple.

Problem: A woman may not be able to predict her responses to pregnancy and childbirth before hand, and may change her mind once the child is born.

'Embryo Transfer to a Host Uterus': a fertilized ovum conceived by couple is implanted into the surrogate mother's uterus.

In Vitro FertilizationSperm and oocyte joined in a laboratory dish, then placed in the oocyte donor's uterus (or another woman's uterus.)

First 'test tube baby' born in 1978.

A woman might undergo IVF if her ovaries and uterus work but her uterine tubes are blocked. A physician removes several of the largest oocytes and sperm are applied.

If sperm cannot penetrate, they are injected. This is called intracytoplasmic sperm injection. It is helpful for males with low sperm count or abnormal sperm.

ICSI has about a 30% success rate.

One or two of the fertilized oocytes are then injected into the woman's uterus.

Cost: $6,500-$15,000. Success Rate: 29%

In Vitro Fertilization, cont'd

Intracytoplasmic Sperm Injection:

A single cell is injected into the cytoplasm of an oocyte.

In Vitro Fertilization, cont'd

Children born following IVF have twice the rate of birth defects (About 9%).

Measures that improve the chance that IVF will culminate in birth include: Transferring the embryos at a slightly later stage, culturing fertilized ova with other cells that normally surround the oocyte, and screening early embryos for abnormalities.

Embryos resulting from IVF can be frozen. The longest and embryo has been frozen, stored and then successfully revived is 13 years.

Gamete and Zygote Intrafallopian Transfer

IVF may fail because of the artificial environment for fertilization.

Gamemte intrafallopian transfer- GIFT improves the setting.

Fertilization is assisted in GIFT, but it occurs in the womens body rather than in glassware.

In GIFT, a woman has several of her largest oocytes removes. The man submits a sperm sample, and the most active cells are separated from it. The two are deposited together into the uterine tube. 27% success rate.

Variation: Zygote Intrafallopian Transfer (ZIFT). IVF ovum introduced to woman's uterine tube and allowed to make its own way to the uterus. 29% success rate.

Oocyte Bank and DonationOocytes can be stored, as sperm are, but the procedure may introduce problems.

Oocytes are frozen in nitrogen, which can cause it to lose a chromosome.

To avoid the difficulties of freezing oocytes, strips of ovarian tissue can be frozen, stored, thawed, and re implanted at various sites, such as under the skin of the forearm, abdomen, or in the pelvic cavity.

Women can also obtain oocytes from donors, typically younger women. Often these women are undergoing IVF and have 'extra' harvested oocytes.

PreImplantation Genetic Diagnosis

A test called preimplantation genetic diagnosis (PGD) detects genetic and chromosomal abnormalities before pregnancy starts.

PGD is possible because one cell, or blastomere, can be removed for testing from an 8-celled embryo, and the remaining 7 cells can complete development normally in the uterus.

Before the embryo is implanted into the woman, the single cell is karyotyped, or its DNA amplified and probed for particular genes that the parents carry.

Today, PGD is increasingly being used to screen fertilization ova and early embryos derived from IVF for chromosome abnormalities before implanted them into the women.

PreImplantation Genetic Diagnosis

A single cell is removed for assessment.

Some Assisted Reproductive Technologies

Various ARTs, ranging in price from $125-$17,000.

Extra EmbryosSometimes assisted reproductive technologies work TOO well. This leaves 'extra' embryos that are not implanted into the uterus.

Fertility clinics can either discard or store them indefinitely

In the US, nearly 500,000 embryos sit in freezers, some for years.

Sometimes they can be donated to couples that can't conceive

They can also be donated for scientific research.

IVF is major source of fertilized ova, however, a new technique called Polar body biopsy allows oocytes to be tested for undesirable traits before they are fertilized. This could reduce the amount of embryos that must be discarded.

ARTs are still very controversial, and raise some ethical issues.

Works CitedLewis, Ricki, 2007, Human Genetics, McGraw Hill, New York, NY, 448.