Biological control

• Artificial insemination (AI)


  Insertion of donated sperm directly into the uterus
• Barrier methods


  Methods of contraception which physically prevent sperm from reaching an ovum
• Contraception


  Prevention of fertilisation by physical or chemical methods
• Intra-uterine devices (IUD)


  Method of contraception which prevents implantation of a blastocyst into the endometrium
• In vitro fertilisation (IVF)


  Procedure involving fertilisation of eggs by sperm in laboratory containers
• Intracytoplasmic sperm injection (ICSI)

  Injection of sperm directly into an egg during IVF
• Pre-implantation genetic diagnosis (PGD)

  Genetic profiling of embryos prior to implantation during fertility treatments
• Tubal ligation


  Sterilisation procedure in which the oviducts are cut and tied
• Vasectomy


  Sterilisation procedure in which the sperm ducts are cut and tied
• Conception depends on many factors interacting together and can lead to infertility
• Our knowledge of the biology of fertilisation can be put to good use when designing treatments for infertility and when developing effective methods of contraception
• Continuous fertility


  Males are described as being continuously fertile because they produce sperm continuously from puberty onwards
• Cyclical fertility


  Females have cyclical fertility, due to the variation in both ovarian and pituitary hormones during the menstrual cycle
• Females are fertile for only a few days each month
• Fertile period


  The fertile period lasts for approximately 5 days around the time of Ovulation
• Calculating the fertile period

  1. Body temperature

  2. Cervical mucus
• Women show cyclical fertility leading to a fertile period. Men show continuous fertility
• Women are only fertile for a few days during each menstrual cycle. Men continually produce sperm in their testes so show continuous fertility
• A woman's body temperature rises by around 0.5°C after ovulation and her cervical mucus becomes thin and watery
• Infertility


  About 10% of all couples are infertile
• Stimulating Ovulation


  1. Drugs which prevent the negative feedback effect of oestrogen on FSH secretion

  2. Drugs which mimic the action of FSH (and to a lesser extent, the effects of LH)
• Super ovulation


  Condition where multiple follicles develop and multiple eggs are released
• Super ovulation can result in multiple births
• Artificial Insemination


  Semen is collected and inserted into the female reproductive tract using a catheter
• Intra-cytoplasmic Sperm Injection (ICSI)

  A healthy sperm cell is injected directly into an ovum
• In vitro fertilisation (IVF)

  Ova are surgically removed, mixed with sperm in a culture dish, and the resulting embryos are screened and implanted into the uterus
• 2 or 3 viable embryos are placed into the female's uterus to increase the chance of successful implantation
• Implanting 2 or 3 embryos can result in multiple births
• Pre-implantation Genetic Diagnosis (PGD)

  Cells are removed from embryos and tested for genetic abnormalities to identify the most suitable embryos for implantation
• Barrier methods


  Condom, diaphragm, cervical cap
• Intra-uterine devices (IUD)


  Small device inserted into the uterus, containing copper or synthetic hormone
• Rhythm method


  Avoiding intercourse during the fertile period by charting changes in cervical mucus and body temperature
• Sterilisation


  Vasectomy (males), Tubal ligation (females)
• Combination contraceptive pill


  Contains synthetic oestrogen and progesterone, suppresses ovulation
• Progesterone-only pill


  Contains only synthetic progesterone, thickens cervical mucus
• Morning-after pill


  Contains high doses of synthetic oestrogen and progesterone, suppresses ovulation and prevents implantation