(See related pages)
|
|
|
| 21.1 New Ways to Make BabiesGrandmother and Mother at the Same Time 1. Arlette Schweitzer became a gestational mother to her genetic grandchildren after she carried to term her daughter's embryo that was fertilized by IVF with her son-in-law's sperm. Midlife Motherhood 1. Rosanna Della Corte became a mother at 62 using a donor embryo fertilized by her husband's sperm. A Five-Year Wait 1. Pamela and Jonathon Loew's route to parenthood involved unsuccessful attempts with a variety of reproductive technologies. They were finally able to conceive using the gamete intrafallopian transfer (GIFT) procedure. 21.2 Infertility and Subfertility 1. Infertility is the inability to conceive a child after a year of trying. 2. The cause of infertility can be determined about 90% of the time. The male contributes about 30% of the time, the female 60%, or both partners may be involved. 3. Subfertility is used to describe couples that conceive unaided, but require a longer time to succeed. Male Infertility 1. Male infertility is due to low sperm count or sperm that cannot swim or are abnormal in structure. 2. Thirty to forty percent of the cases of male infertility involve deletions of genes involved in spermatogenesis located on the Y chromosome. 3. Infertility affects about 4% of men. Female Infertility 1. Female infertility can be due to an irregular menstrual cycle or blocked fallopian tubes. 2. Fibroid tumors, endometriosis, or a misshapen uterus may prevent implantation of a fertilized ovum, and secretions in the vagina and cervix may inactivate or immobilize sperm. 3. Oocytes may fail to release a sperm-attracting biochemical. 4. Early pregnancy losses due to abnormal chromosome number may be mistaken for infertility; this is more common among older women. Infertility Tests 1. Medical tests to identify the cause of infertility are conducted on the male first. Sperm are checked for number, motility, and morphology. PCR analysis of the Y chromosome may reveal deletions. 2. If the male is fertile, a gynecologist will examine the structures of the woman’s reproductive system and conduct tests to assess female infertility. 21.3 Assisted Reproductive TechnologiesDonated Sperm - Artificial Insemination 1. In artificial insemination, donor sperm are placed into a woman's reproductive tract. 2. X-bearing and Y-bearing sperm can be enriched to enhance sex selection. A Donated Uterus-Surrogate Motherhood 1. A genetic and gestational surrogate mother is artificially inseminated with sperm and provides her uterus for nine months. 2. A gestational surrogate carries a fetus conceived in vitro with gametes from the genetic parents. In Vitro Fertilization (IVF) 1. In IVF, a sperm and an oocyte meet in a laboratory dish and an early embryo is then transferred to the uterus. 2. Intracytoplasmic sperm injection (ICSI) can enable immobile sperm to fertilize an oocyte. 3. Preimplantation embryos can be frozen for later use. Gamete Intrafallopian Transfer 1. In GIFT, sperm and oocytes are placed together in a fallopian tube past a blockage. 2. In ZIFT, a preimplantation embryo conceived in vitro is placed in a fallopian tube. Oocyte Banking and Donation 1. The oocytes used for IVF can be donated. 2. Embryo adoption involves an oocyte donor who is artificially inseminated. The donor then has a preimplantation embryo washed out of her uterus and transferred to the gestational mother. 3. Cytoplasmic donation is a technology that is used to rejuvenate the oocytes of older women with the injected cytoplasm of oocytes from a younger woman. Preimplantation Genetic Screening and Diagnosis 1. Cells can be removed from early embryos and screened for genetic and chromosomal abnormalities (preimplantation genetic diagnosis, PGD). 21.4 On the Subject of "Spares" 1. "Spare" embryos from IVF attempts might be discarded or used for research. 2. Polar body biopsy can be used to genotype the oocyte. 3. Oocytes free of genetic disorders can be fertilized in vitro. PGD can confirm the "health" of the embryo. |