Development of assisted reproductive technology
2019-11-01
Since July 25, 1978, Louise Brown, the world's first live birth-through test tube baby, was born in a hospital in Manchester, England. In vitro fertilization (IVF) or commonly known as "Test tube baby" technology has been used for more than 40 years. The first generation of "test tube baby" technology has gradually evolved into the second and third generation of "test tube baby" technology. Therefore, July 25 of each year is identified as "World Embryologist Day."
Method of treating infertility in IVF
Before the IVF technology was used as a clinical treatment for infertility, the basic research of the predecessors laid a good foundation. In 1959, Chinese-born Chinese biologist Min Chueh Chang combined the sperm and eggs recovered from rabbit mating in vitro, and he also transplanted the fertilized eggs into the fallopian tubes of other rabbits. Young rabbit. Successful completion of rabbit in vitro fertilization experiments made Zhang Minjue a pioneer in in vitro fertilization research. Before the ovulation of the female rabbit and at different times after ovulation, the sperm or epididymal sperm injected from the male rabbit is introduced into the fallopian tube of the female rabbit to fertilize the egg. The experimental results showed that only the sperm placed in the fallopian tube 6 hours before ovulation can be fertilized with the egg, indicating that rabbit sperm need at least 6 hours to develop fertilization ability in the reproductive tract of the female rabbit. This experiment made Zhang Minjue realize that for mammals, it is actually the sperm waiting for the egg in the fallopian tube, rather than the egg waiting for the sperm. The sperm must undergo some physiological changes in the female reproductive tract to be fertilized with the egg. This is the phenomenon of "sperm capacitation". His animal experiment results laid a good foundation for later in vitro fertilization and IVF research.
The birth of the first test-tube baby in the world
After the birth of Louis Brown in England in 1978, the first test-tube baby, Candice Reed, was born in June 1980. In June 1978, Howard and Georgen Jones of the United States established the Department of Reproductive Medicine at the Southern Virginia Medical School in Norfolk, and began the IVF project. In December 1981, the first IVF in the United States was born. The first test-tube baby in France was born in Clamart in 1982, and the second was born in Sevres in June of the following year. China’s work in this area was relatively late. In 1985, the first test-tube baby was born in Taiwan. In 1986, Hong Kong was also born in 1 case. Zheng Mengzhu, the first test-tube baby in the mainland, was born in the Third Hospital of Northern Medicine in March 1988. He gave birth to a baby boy in April 2019.
Assisted reproductive technology for infertility patients
Medicine is an emerging discipline that has been differentiated from obstetrics and gynaecology at the end of the 20th century. It is based on the theory of reproductive endocrinology and focuses on assisted reproductive technology (ART), which uses medical techniques and methods for gametes. The zygote and embryo are manually manipulated to achieve the technique of conception of pregnancy, that is, the method of assisting one or all of the natural processes by artificial means to complete the method of reproduction.
ART includes artificial insemination (AI), IVF-ET, intracytoplasmic sperm injection (ICSI), pre-plant genetic diagnosis (PGD), and immature oocyte in vitro culture maturation (IVM) techniques.
Artificial insemination
Artificial Insemination (Al) refers to the method of artificially injecting male semen into the cervix or uterine cavity of a woman to assist in conception. Its main purpose is to allow women to insemination to the vagina or uterus without pregnancy. According to different semen sources, artificial insemination is divided into artificial insemination by husband semem (AIH) and artificial insemination by donor semem (AID). Intrauterine insemination (IUI) is a more common method. This method is relatively simple, the treatment cycle is short, the cost is low, the patient does not have to endure the pain of surgery, the combination of sperm and egg and the development of the embryo are completed in the patient. In 1786, Dr. Hunter of the United Kingdom implemented the first human artificial insemination of fertilization. In 1866, Dr. Sims implemented the first human artificial insemination of fertilization.
AIH is mainly suitable for husbands suffering from impotence, premature ejaculation, retrograde ejaculation, hypospadias, etc., but normal or mild abnormalities of semen; female congenital or acquired genital malformations and cervical infertility can also be used AIH. AID is mainly suitable for husbands with azoospermia or hereditary diseases as well as blood group incompatibility or immune infertility.
In vitro fertilization-embryo transfer technique
In vitro fertilization-embryo transfer (IVF-ET), commonly known as "first-generation IVF technology", refers to the use of medical techniques to in vitro fertilization of eggs and sperm and early embryo development, and then embryos A technique for transplanting into a female uterus to make it successful. It is mainly suitable for infertility patients caused by female factors such as fallopian tube obstruction and endometriosis. IVF-ET includes four stages: ovulation induction, egg retrieval, in vitro fertilization and in vitro culture, and embryo transfer.
In 1968, Edwards met the British laparoscopic expert Patrick Steptoe, who was good at using laparoscopic techniques to remove mature eggs from the ovaries of infertile women, and the two began long-term cooperation. After several failures, they finally succeeded in in vitro fertilization and obtained fertilized eggs that could be split. In 1972, two people began transplanting embryos in test tubes into the mother. In 1977, two individuals who had infertility for many years had an in vitro fertilization-embryo transplant. Mrs. Brown was pregnant and gave birth to the world's first test-tube baby the following year. To this end, the British physiologist Professor Edwards was awarded the Nobel Prize in Physiology or Medicine in 2010 for his special contribution to IVF technology.
Cytoplasmic sperm injection
Intracytoplasmic sperm injection (ICSI). This technology, also known as microinsemination, commonly known as "second generation IVF technology", is a technique of injecting a single sperm into the cytoplasm of an egg under a microscope to form a fertilized egg and then transplant it into the female uterus. This technology mainly solves the problem of infertility caused by men with less sperm, weak sperm, abnormal sperm or spermlessness and sperm fertilization from the source of testicular puncture and microsurgery.
In 1992, Palermo of the Belgian Free University of Belgium used the ICSI method to assist in the successful fertilization. The first report of ICSI is the treatment of infertility caused by severe male factors that conventional IVF cannot solve, marking a new milestone in ART research.
Preimplantation genetic testing
Preimplantation genetic diagnosis (PGD), commonly known as "third generation of IVF technology", this technology mainly solves the genetic diagnosis and eugenic problems before embryo implantation. It is an embryo formed after in vitro fertilization under microscopic operating system, biopsy cleavage stage or polar or blastocyst stage cells before and after fertilization, using molecular biology techniques, PCR or FISH methods to determine DNA fragments or specific chromosomes. Rapid genetic diagnosis, transplantation of embryos diagnosed with no genetic disease into the uterus. Preimplantation genetic testing mainly includes two strategies, namely preimplantation genetic diagnosis (PGD) and preimplantation genetic screening (PGS). PGD indications include monogenic diseases, X-linked genetic diseases, HLA matching, etc.; and PGS is suitable for people with repeated abortions, repeated transplant failures, and older women. In 1989, British scholar Handyside successfully completed the world's first PGD, creating a new era of prenatal diagnosis.
In addition to routine biopsy methods to obtain samples, there is now a new noninvasive chromosome screening (NICS). The method is based on gene sequencing of DNA released into blastocyst culture medium, and is amplified by MALBAC whole genome, and then subjected to high-throughput sequencing, which confirms that the blastocyst culture solution is highly consistent with the chromosomal abnormality detection result of the corresponding embryo. .
Oocyte cytoplasmic replacement technique
Commonly known as the "fourth generation of IVF" technology, the egg yolk of the egg is replaced with the healthy egg cytoplasm of another woman by micromanipulation technology to enhance the vitality of the egg and improve the success rate of conception. In 2016, Zhang Jin et al. obtained the available embryos and the final pregnancy in patients who had embryonic cessation in two consecutive IVF-ET assisted pregnancy treatments through pronuclear transplantation. Since the mitochondrial DNA in the egg cytoplasm of the donor is brought into the egg cell, causing widespread controversy around the world, caution should be exercised before the exact effect of the technology is clear. Most countries, including China, currently ban the clinical application of this technology.
Immature egg culture in vitro (IVM)
The IVM technique simulates the growth environment of the oocyte in vivo, obtains immature oocytes from the ovary, matures in vitro, and is used for in vitro fertilization-embryo transfer. This technique overcomes the ovarian hyperstimulation syndrome induced by controlled superovulation drugs and The risk of hormone-dependent tumorigenesis can also be used to preserve the ovarian reproductive capacity of people with ART and tumors with low ovarian response.
Embryonic, gamete and gonadal tissue freeze-thaw technology
In the field of reproduction, cryopreservation of embryos and gametes is an important part of human ART, including embryo cryopreservation, sperm freezing, mature egg cryopreservation, immature egg cells and ovarian tissue cryopreservation. At present, the freezing and resuscitation of embryos has become one of the conventional techniques of ART. The freezing methods used include slow freezing method, rapid freezing method, ultra-rapid freezing method and vitrification freezing method. Vitrification freezing technology is a method for rapidly freezing cells or tissues, which avoids the formation of intracellular ice crystals during freezing and thawing, and minimizes cell damage. Therefore, in recent years, vitrification has been widely used in human gametes, embryos, etc. The clinical study of cryopreservation has made a lot of progress.
