1.8 Flashcards
Some men are infertile because they produce semen containing a large number of
abnormal sperm
Abnormal sperm may have
structural changes
may not be able to swim properly
Other infertile men may produce semen containing very few sperm cells caused by many factors:
Blockage of vasa deferentia (injury/disease) Infectious diseases (STDs/from childhood-mumps) Hormonal dysfunction Chronic diseases (diabetes/hypertension) Varicocele (swelling that appears on 1 or both testicles)
The inability to obtain or maintain an erection, can also cause male infertility, known as -
Erectile dysfunction (ED)
Male infertility can be treated by
surgery if vasa deferentia is suspected
If a man produces some healthy sperm -
IVF may be carried out using selected sperm
Reasons why women may be infertile are:
Abnormal menstrual cycles
Blockage of the oviducts
Abnormal menstrual cycles cause infertility as
do not produce enough hormones, this may mean that they do not ovulate or rarely ovulate
Blockage of the oviducts may be caused by
bacterial infections, e.g. gonorrhoea or chlamydia
Ways to overcome blockage of oviducts
surgery
IVF
IVF stands for:
In Vitro Fertilisation
IVF usually occurs in
flat glass dishes
In IVF, sperm and oocytes are mixed together in a glass dish and embryos are then
returned to the woman’s uterus
(IVF) sometimes a man produces very few healthy sperm, or the sperm are not capable of fertilising the oocyte by themselves. In this case a sperm may be injected into the oocyte using a very tiny needle, known as -
Intra-cytoplasmic sperm injection (ICSI)
IVF 1) Woman is given hormone (FSH) injections that cause several follicles to develop in her ovary. Hormone injections are usually given…
for about 10 days
IVF 2) When the follicles have matured adequately, another hormone injection is given, which is similar to LH therefore brings about
ovulation
IVF 3) The mature oocytes are collected from the ovary using a needle. This is inserted into the vagina and is guided into place using
ultrasound
IVF 3 MALE) Semen is collected. it is washed and then placed in a liquid containing nutrients and substances that allow the sperm to become
capacitated
IVF 4) The sperm and oocytes are placed together in a culture medium for about 18 hours. During this time…
fertilisation should take place
IVF 5) The fertilised egg is passed to a special growth medium and left for about 4-8 hours until the egg has reached the
6-8 cell stage
IVF 6) The embryos judged to be the ‘best’ are transferred to the uterus through a catheter through her vagina and cervix. Usually 2 embryos are transferred. Any extra embryos may be preserved by
freezing in liquid nitrogen
During IVF sperm cells are washed because it
separates the sperm from other components in the semen and reduces the chance of passing on infections
In IVF sperm cells are placed in a medium that allows them to become capacitated because it allows
changes to take place in the membrane surrounding the sperm head - acrosome reaction can occur and the sperm is able to penetrate the oocyte
A large number of oocytes are collected at one time because it is an
invasive process that takes place under sedation or general anaesthetic
Only 2 embryos are usually replaced in the uterus, because anymore would
lower the chance of a successful pregnancy
