Infertility and assisted reproductive technologies ·… | StemPy Lab
Course 21.2·Lesson 3 of 3
Infertility and assisted reproductive technologies
Many couples cannot have a child, for many different reasons. Doctors may help them with assisted reproductive technologies. In IVF, the ovum and the sperms meet in a laboratory, and the embryo is placed in the body of the woman. This lesson shows where each technique places the gametes or the embryo.
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When a couple cannot have a child
There are many couples in the world who are unable to have a child even though they live together and do not use any contraceptive. This is called infertility. Medical books usually say that a couple is infertile if a pregnancy has not come after 12 months of regular, unprotected intercourse. The World Health Organization estimates that about 1 in 6 people in the world is affected by it at some time in life.
The cause may lie with the woman, with the man, or with both. NCERT lists these causes: physical, congenital, diseases, drugs, immunological and psychological. Special health care units, the infertility clinics, find the cause and treat what can be treated.
When the usual treatment cannot help, a couple may be helped by assisted reproductive technologies (ART).
In vitro fertilisation and embryo transfer
In IVF (in vitro fertilisation), the word in vitro means in glass, outside the body. This is the method called the test tube baby programme.
An ovum is collected from the wife, or from a donor, and sperms are collected from the husband, or from a donor.
The two are brought together in a dish, in conditions like those of the body. The ovum is fertilised and forms a zygote.
The zygote divides in the laboratory. The cells of the early embryo are called blastomeres.
The zygote, or the early embryo, is transferred into the woman's body. This is the embryo transfer (ET).
A flow chart. Two boxes on the left, the ovum from the wife or from a donor and the sperms from the husband or a donor, have arrows to a box in the middle that says joined in a dish in the laboratory, in vitro. An arrow down leads to a box, zygote or early embryo. From it, two arrows lead to the right. The upper box says 8 blastomeres or fewer, into the fallopian tube, ZIFT. The lower box says more than 8 blastomeres, into the uterus. A line at the bottom says that development goes on in the body of the mother.
The first baby that was born from an IVF was Louise Brown, in England in 1978. Robert Edwards, whose work made it possible, received the Nobel Prize in Physiology or Medicine in 2010.
ZIFT, and the transfer to the uterus
Where the embryo is placed depends on its age. NCERT gives the rule.
A zygote, or an early embryo of up to 8 blastomeres, is transferred into the fallopian tube. This is ZIFT, zygote intra fallopian transfer.
An embryo of more than 8 blastomeres is transferred into the uterus. This is called intra uterine transfer (IUT).
Embryos that are formed in the body, by fertilisation inside the female (in vivo fertilisation), can also be taken and used for such a transfer, to help females who cannot conceive.
You should find that the numbers of blastomeres are 1, 2, 4, 8, 16, 32 and 64, and that the change from the tube to the uterus comes between 8 and 16.
GIFT
GIFT is gamete intra fallopian transfer. The ovum of a donor is transferred into the fallopian tube of a woman. She cannot produce an ovum of her own, but she can provide a suitable place for fertilisation and for the growth of the embryo. In GIFT, fertilisation takes place inside the body, in the tube.
Techniques that are not in the NEET text
The NEET syllabus names IVF, ZIFT and GIFT. The techniques in this part are in NCERT and are asked in other exams, but they are not in the NEET text.
ICSI (intra cytoplasmic sperm injection). One sperm is injected directly into an ovum in the laboratory, and the embryo is then transferred.
Artificial insemination (AI). Semen from the husband, or from a healthy donor, is placed in the vagina. It helps when the male partner cannot inseminate the female, or when the sperm count in the semen is very low.
Intra uterine insemination (IUI). The semen is placed in the uterus. It is a form of artificial insemination.
A front view of the female reproductive tract: the uterus, two fallopian tubes, two ovaries and the vagina. Green arrow from the text at the top left to a fallopian tube: ZIFT, a zygote or an embryo of up to 8 blastomeres into the tube, and GIFT, an ovum from a donor into the tube. A blue arrow to the cavity of the uterus: IUI, semen into the uterus, and IUT, an embryo of more than 8 blastomeres into the uterus. A red arrow to the vagina: AI, semen into the vagina. A grey note says that IVF and ICSI embryos are made in the laboratory and then transferred.A drawing of intra cytoplasmic sperm injection. A large ovum with a pale outer layer, a golden cytoplasm and a red nucleus is held still on the left by a holding pipette. A fine needle comes from the right and carries one sperm, a blue oval with a tail, into the cytoplasm of the ovum. Labels say that the holding pipette keeps the ovum still, and that the fine needle places one sperm inside the ovum. A line at the bottom says that the embryo that forms in the laboratory is then transferred.
Things to think about
The ART help many couples, but they are costly. They do not always succeed. They also raise emotional, religious and social questions, and many countries control them by law. Adoption is another way to have a child in the family.
Try it in Python
The program finds the number of blastomeres after a number of divisions, and the site where the embryo is transferred.
Practise with new numbers
Common mistakes
Saying that fertilisation in IVF takes place in the body. It takes place in a dish in the laboratory.
Mixing up ZIFT and GIFT. ZIFT places a zygote or an early embryo in the tube. GIFT places the ovum of a donor in the tube.
Putting an embryo of 16 cells in the fallopian tube. The tube is for up to 8 blastomeres. A larger embryo goes into the uterus.
Saying that ICSI places the semen in the vagina. ICSI puts one sperm into the ovum. The semen goes into the vagina or the uterus in artificial insemination.
Saying that every case of infertility is the fault of the woman. The cause may lie with the man, with the woman or with both.
Remember these
Infertility: no child in spite of unprotected intercourse. The causes are physical, congenital, diseases, drugs, immunological and psychological.
IVF: fertilisation in the laboratory, then embryo transfer. The "test tube baby" method.
ZIFT: a zygote or an embryo of up to 8 blastomeres goes into the fallopian tube. More than 8 blastomeres: into the uterus.
GIFT: the ovum of a donor goes into the fallopian tube.
ICSI: one sperm is injected into an ovum. AI and IUI: semen is placed in the vagina or the uterus.
Check yourself
Try each one on your own first. If you are stuck, open a hint. Then check with Show the answer.
What does IVF stand for, and where does the fertilisation take place?
Where is a zygote of 6 cells placed, and where is an embryo of 16 cells placed?
How does GIFT differ from ZIFT?
Name three of the causes of infertility that NCERT lists.
What is ICSI?
References
NCERT (2023). Biology, Textbook for Class XII, chapter 3, Reproductive Health.
World Health Organization (2023). Infertility prevalence estimates, 1990 to 2021, and the WHO definition of infertility (Zegers-Hochschild F. et al., 2017, The International Glossary on Infertility and Fertility Care).
Nobel Prize Outreach (2010). The Nobel Prize in Physiology or Medicine 2010: Robert G. Edwards.
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