· It is a prenatal diagnostic technique for detecting genetic or other foetal disorders and sex of the foetus based on the chromosomal pattern in the amniotic fluid in the amniotic sac surrounding the developing embryo.
Procedure of the Amniocentesis
i. The location of the foetus and placenta are determined by sonography at the early stage of the pregnancy.ii. A local anaesthetic can be given to the mother to relieve pain during the insertion of the needle.
iii. Then a small amount of amniotic fluid (about 20 cc) that surrounds the foetus (embryo of animal) is withdrawn with the help of a hypodermic needle (special surgical needle) passed through the abdominal wall and uterine wall into the amniotic sac containing amniotic fluid without causing any damage to the foetus. Amniotic fluid contains live foetal skin cells and other substances such as alpha-fetoprotein (AFP).
iv. The fluid is centrifuged to concentrate the foetal cells.
v. The foetal cells are cultured under test tube conditions to obtain more of them.
vi. The foetal cells are analyzed in two ways:
(a) Karyotype analysis: This is used to detect the chromosomal abnormalities (Down’s syndrome, Klinefelter’s syndrome etc) in a growing embryo.
· It is also helpful in the determination of the sex of an unborn baby on the basis of the presence or absence of sex chromatin.
(b) Biochemical Test: It is used to detect the presence or absence of certain enzymes or metabolic features.
(b) Biochemical Test: It is used to detect the presence or absence of certain enzymes or metabolic features.
· It is useful for the detection of prenatal diseases (Sickle cell anaemia, Phenylketonuria, Haemophilia) of the foetus.
Associated Risks and Side Effects
1. Miscarriage is the primary risk related to amniocentesis due to infection in the uterus, the water breaks or labour being induced prematurely.
2. Sometimes needle may come in contact with the baby. So, precaution should be taken while using a sonogram to guide the needle away from the baby.
3. The mother may experience sharp pain when the needle pierces the skin and uterus.
4. Other side effects include cramping, fluid leakage, minor irritation around the punctured site.
5. A raised temperature or general feeling of unwell occurs.
6. If the results are abnormal, terminate the pregnancy after consulting with a genetic doctor or counsellor.
1. Miscarriage is the primary risk related to amniocentesis due to infection in the uterus, the water breaks or labour being induced prematurely.
2. Sometimes needle may come in contact with the baby. So, precaution should be taken while using a sonogram to guide the needle away from the baby.
3. The mother may experience sharp pain when the needle pierces the skin and uterus.
4. Other side effects include cramping, fluid leakage, minor irritation around the punctured site.
5. A raised temperature or general feeling of unwell occurs.
6. If the results are abnormal, terminate the pregnancy after consulting with a genetic doctor or counsellor.
· Amniocentesis is generally offered in the following conditions:
a) When a pregnant woman is over 35 years of age as there is more risk of having a child with Down’s syndrome.
b) When a mother has already given birth to an abnormal foetus.
c) When a mother has a family history of genetic diseases (Down’s syndrome, Muscular dystrophy, Haemophilia etc.) and certain birth defects.
d) For avoiding the abnormalities that are most common in particular racial groups e.g. haemoglobin deficiencies in the black.
Advantages of Amniocentesis
i. It is used to detecting chromosomal abnormalities (disorders) such as Down’s syndrome, spina bifida (open spine where vertebrae fail to close), anencephaly (incomplete development of the brain) and more than 300 genetic diseases.
ii. It is also used to detect metabolic disorders such as sickle cell anaemia, alkaptonuria, phenylketonuria etc.
iii. It is used for the determination of the sex of the unborn child in advance. It is the most accurate way to determine the baby’s gender before birth.
iv. Amniocentesis also provides access to DNA for paternity testing prior to delivery.
i. It is used to detecting chromosomal abnormalities (disorders) such as Down’s syndrome, spina bifida (open spine where vertebrae fail to close), anencephaly (incomplete development of the brain) and more than 300 genetic diseases.
ii. It is also used to detect metabolic disorders such as sickle cell anaemia, alkaptonuria, phenylketonuria etc.
iii. It is used for the determination of the sex of the unborn child in advance. It is the most accurate way to determine the baby’s gender before birth.
iv. Amniocentesis also provides access to DNA for paternity testing prior to delivery.
· DNA is collected from the paternal father and is compared to DNA obtained from the baby during amniocentesis.
· The results are accurate (99%) for determining paternity.
· Haemophilia, colour blindness, alkaptonuria, phenylketonuria, albinism, sickle cell anaemia are caused by a single gene mutation.
· Down’s syndrome, Turner’s syndrome, Klinefelter’s syndrome are caused by chromosomal aberrations.
· Down’s syndrome, Turner’s syndrome, Klinefelter’s syndrome are caused by chromosomal aberrations.
Disadvantages of Amniocentesis
· The main disadvantage of amniocentesis is it is being misused to abort the normal foetal foetuses.
· So, it has been legally banned for the determination of sex to avoid female foeticide.
Down’s Syndrome (Mongolism or Trisomy 21)
· It is caused due to extra chromosome 21 (so also called trisomy 21).
· Individuals have 47 chromosomes on body cells suffering from it.
· Its incidence increases with the age of the mother (more risk after the age of 40). The child shows many abnormalities in facial structures such as flattened nasal bridge, habitually open mouth, protruding tongue, short and broad neck etc.
· Down’s syndrome is a congenital syndrome originating from the non-disjunction of chromosomes of pair 21 during meiosis.
· The mongoloids, therefore, have 47 chromosomes instead of 46 with three copies of chromosome 21 instead of the usual two.
· There is strong evidence that this extra 21 chromosome comes from the abnormal egg produced mostly in the aged females.
· At the time of meiosis, the homologous chromosomes of the 21st pair fail to separate and are transmitted together to the egg. Such eggs, therefore, contain 23+1 chromosomes (trisomy).
· When such an egg is fertilized with a normal sperm with 23 chromosomes, the zygote formed has 46+1=47 chromosomes.
· Its incidence increases with the age of the mother (more risk after the age of 40). The child shows many abnormalities in facial structures such as flattened nasal bridge, habitually open mouth, protruding tongue, short and broad neck etc.
· Down’s syndrome is a congenital syndrome originating from the non-disjunction of chromosomes of pair 21 during meiosis.
· The mongoloids, therefore, have 47 chromosomes instead of 46 with three copies of chromosome 21 instead of the usual two.
· There is strong evidence that this extra 21 chromosome comes from the abnormal egg produced mostly in the aged females.
· At the time of meiosis, the homologous chromosomes of the 21st pair fail to separate and are transmitted together to the egg. Such eggs, therefore, contain 23+1 chromosomes (trisomy).
· When such an egg is fertilized with a normal sperm with 23 chromosomes, the zygote formed has 46+1=47 chromosomes.
TEST TUBE BABY
· In some cases, women are unable to conceive. This is due to fertilization in such women is not possible in the ampulla of the fallopian tube or fallopian tubes are degenerated, or the sperms of males are not strong enough to fertilize the ovum.· So, fertilization is allowed outside the body. It is also called in vitro fertilization (fertilization outside the body).
· So, a test tube baby is a child that is conceived outside the body of the female.
· The first attempt to produce a test tube baby was made by an Italian scientist Dr Petrucci in 1959 A.D., although the embryo survived for 29 days.
· The first attempt to produce a test tube baby was made by an Italian scientist Dr Petrucci in 1959 A.D., although the embryo survived for 29 days.
· In vitro fertilization technology, propounded by Prof. Robert Winston, was used by Patric Steptoe and Robert Edwards (England) to produce the world's first female test-tube baby, Louise Joy Brown, on July 25, 1978 A.D.
· Later other test-tube babies were produced in Australia, the United States and other countries.
· In Nepal, Om Mani Tamang who was born on March 3, 2005, at Om Hospital was the first test-tube baby.
· Later other test-tube babies were produced in Australia, the United States and other countries.
· In Nepal, Om Mani Tamang who was born on March 3, 2005, at Om Hospital was the first test-tube baby.
· At present, there are nearly 200 Nepali children born through this process.
Causes of Infertility in Males
i. A low sperm count (less than 20 million sperms/cm3)
ii. Production of a large number of abnormal sperms (more than 4%)
iii. Production of antibodies that stick the sperms together.
i. A low sperm count (less than 20 million sperms/cm3)
ii. Production of a large number of abnormal sperms (more than 4%)
iii. Production of antibodies that stick the sperms together.
Causes of Infertility in Females
i. The pituitary fails to produce FSH for the development of the ovarian follicles so there is failure to ovulation.
ii. Fallopian tubes are damaged, narrowed or blocked or diseased.
iii. Uterus is damaged so unable to maintain pregnancy. Due to this, the fertilized egg (zygote) does not get implanted.
iv. Cervical mucus, that halts, repels or kills sperms.
· In vitro: A process, test or procedure in which something is measured or observed outside the living organism.
· In vivo: A process, test or procedure in which something is measured or observed inside the living organism.
IVF Technology involves the following steps:
(a) Taking out eggs from the ovary by using ultrasound or laparoscopic guidance.
(b) Culture of eggs in vitro in an incubator for maturation.
(c) Fertilization of eggs in test tubes from the semen obtained from males.
· The gametes require 14–18 hours to fertilize. After fertilization, the zygote is kept in another fluid at body temperature.
· When the zygote reaches 32 celled stages, it is implanted into the uterus of another female which serves as host or surrogate other. After the normal (gestation) period, there is the birth of a normal baby.
· Surrogate mothers do not have any role in the genetic make of a child as the egg comes from the donor mother and sperm from the donor father.
· Surrogate mothers do not have any role in the genetic make of a child as the egg comes from the donor mother and sperm from the donor father.
Advantage of Test Tube Baby
1. Great advancement of medical science
2. Boon to the childless couples
3. Employed to such women who are unable to conceive.
1. Great advancement of medical science
2. Boon to the childless couples
3. Employed to such women who are unable to conceive.
Problems Associated with IVF Technology
1. Surrogate mother gives birth yet the ovum does not belong to her.
2. It has raised many moral and ethical attitudes in the community.
3. Muslim countries believe that sperm donation is immoral.
Also, Read our other Notes on the Application of Biology: