Guidance and guidance
1. In vitro fertilization technology?
Mammalian in vitro fertilization mainly includes oocyte collection, sperm acquisition and fertilization. ?
(1) How to collect oocytes and how to operate them?
The first method: when collecting oocytes from experimental animals, such as mice, rabbits, small domestic animals, pigs, sheep, etc., we can first treat them with gonadotropins to expel more eggs, and then wash them out of the fallopian tubes at an appropriate time and fertilize them directly with the obtained sperm in vitro. ?
The second method: the ovaries are taken from the newly slaughtered female animals, and then the oocytes are collected from the ovaries. ?
The third method: collecting oocytes directly from the ovaries of living animals is called live egg collection. It is necessary to directly suck oocytes from the ovaries of living animals by means of ultrasonic detectors, endoscopes or laparoscopy. ?
The latter two methods are suitable for domestic animals and large animals. The collected oocytes need to be cultured and matured in vitro before they can be fertilized with capacitated sperm. ?
(2) What are the specific methods and requirements for sperm collection?
Mainly divided into fake vagina method, hand holding method and electrical stimulation method. ?
Fake vagina method is to use a special fake vagina to meet the requirements of pressure, temperature and lubrication when male animals mate. At the same time, it is necessary to equip Taiwan Province animals suitable for sperm donors, train animals to climb over Taiwan Province animals and collect semen through fake vaginas. ?
Hand-holding method is to directly grasp the penis of male animals with bare hands or hands with latex gloves, apply appropriate pressure and stimulation to make them ejaculate, and collect semen rich in sperm. ?
The electric stimulation method is to insert a special electrode into the rectum of an animal and directly stimulate the ejaculation center at the waist and recommended parts, which is only suitable for wild or part of economic animals. ?
In addition, for experimental rodents, semen can be collected from the tail of epididymis after execution. ?
(3) How to deal with sperm capacitation?
Before in vitro fertilization, sperm must acquire competence by the following methods:
① Culture method: For the sperm of rodents, rabbits, pigs and other animals, the sperm taken from epididymis is put into the artificially prepared capacitating solution, and after a period of culture, the sperm can be capacitated, which is called culture method. ?
② Chemical induction method: For the sperm of cattle, sheep and other domestic animals, put the sperm into a certain concentration of heparin or calcium ion carrier a23 187 solution, and induce sperm capacitation with chemical drugs, which is called chemical induction method. ?
(4) fertilization?
Generally, capacitated sperm and cultured mature eggs can complete the fertilization process in capacitated fluid or special semen.
2. Fertilization and early embryo culture?
After sperm and egg are fertilized, the fertilized egg should be put into the development medium for further culture. ?
(1) development medium?
Objective: After in vitro fertilization, sperm and eggs are used for continuous culture of fertilized eggs. ?
② Ingredients: water, inorganic salts, organic matter, vitamins, hormones, amino acids, nucleotides, animal serum, etc. ?
(2) Process?
It is roughly as follows: in vitro fertilization → improved bovine early embryos → embryo transfer → healthy recipient cattle → improved calves → mature cattle.
Learn and use it skillfully.
1 Which of the following conditions is unnecessary during the in vitro culture of early embryos ()?
A. Disinfection and sterilization
B.what is the appropriate temperature?
C. adequate light
D. Suitable nutrients and hormones?
Problem solving skills: Animal cells must be cultured in vitro under aseptic conditions. In the process of cell division, appropriate temperature, certain nutrients and hormones are needed, but sunlight is not needed. ?
Answer: c?
Example 2 Which of the following problems can be solved by test-tube animal technology ()?
A. Treating some genetic diseases
B. improve the disease resistance of animals?
C. increase the diversity of animals
D. improve the fertility of improved livestock?
Tips to solve the problem: IVF technology can solve the fertility problem of some infertile patients and improve the fertility of improved livestock, mainly through in vitro fertilization and embryo transfer to the uterus of surrogate mothers. Genetic diseases are mainly treated by gene therapy. Improving the disease resistance of animals means improving immunity, increasing animal diversity and cultivating new animal varieties. This topic is the application of modern reproductive technology in production and life, which requires students to pay attention to hot spots and the application of modern technology in the biological field. ? Answer: d
The first "Tiger, Lion and Beast" in China was born in Nanjing Hongshan Zoo in xx, which was produced by "in vitro fertilization" of male tiger sperm and female lion egg. The problem to be solved in this process is ()?
A. Treating sperm with capacitating substances in vitro?
B. remove the yolk membrane with chemicals to facilitate sperm entry?
C. extract the nuclei of sperm and eggs for fusion?
D. After sperm enters the egg, do manual treatment to prevent too many sperm from entering the egg?
Problem-solving skills: Sperm can only be fertilized after capacitation, so in vitro fertilization needs capacitation; Sperm will naturally form two barriers to prevent multiple sperm from entering the egg. Another change after egg entry is that male pronucleus and female pronucleus are formed respectively, and fertilization is completed after fusion into zygote, rather than pronucleus fusion, so B, C and D are unnecessary. ?
A: A.
Example 4 The statement about industrialized production of bovine in vitro fertilized embryos is correct ()?
A. Sperm and eggs can be fertilized to form fertilized eggs and then moved into cow uterus?
B. The collected oocytes should be immediately put into the culture medium with sperm to form fertilized eggs?
C. The fertilized egg formed when the mature egg meets the collected sperm needs to be cultured to a certain stage before it can be transplanted?
D. industrialized production of in vitro fertilized embryos, that is, embryo development and fertilization only need to be carried out in vitro?
Problem-solving skills: Oocytes can only be fertilized with capacitated sperm after artificial culture in vitro, and fertilized eggs can only be transplanted at the stage of morula or blastocyst, and then continue to develop into larvae after transplantation to the mother. ?
Answer: c