Tissue culture, a method of biological research in which fragments of tissue from an animal or plant are transferred to an artificial Environment in which they can continue to survive and function. The cultured tissue may consist of a single cell, a Population of cells, or a whole or part of an organ. Cells in culture may multiply; change size, form, or function; exhibit specialized activity (muscle cells, for example, may contract); or interact with other cells.
Historical Developments
An early attempt at tissue culture was made in 1885 by German zoologist Wilhelm Roux, who cultivated tissue from a chick embryo in a warm salt solution. The first real success came in 1907, however, when American zoologist Ross G. Harrison demonstrated the Growth of frog nerve cell processes in a medium of clotted lymph. French surgeon Alexis Carrel and his assistant Montrose Burrows subsequently improved upon Harrison’s technique, reporting their initial advances in a series of papers published in 1910–11. Carrel and Burrows coined the term tissue culture and defined the concept. Thereafter, a number of experimenters succeeded in cultivating animal cells, using as culture media a variety of biological fluids, such as lymph, blood serum, plasma, and tissue extracts. In the 1980s and ’90s, methods were developed that enabled researchers to successfully grow mammalian embryonic stem cells under artificial conditions. Those breakthroughs ultimately enabled the establishment and maintenance of human embryonic stem cell lines, which advanced researchers’ understanding of human biology and greatly facilitated progress in therapeutics and regenerative medicine.
Culture Environments Cells may be grown in a culture medium of biological origin such as blood serum or tissue extract, in a chemically defined synthetic medium, or in a mixture of the two. A medium must contain proper proportions of the necessary nutrients for the cells to be studied and must be appropriately acid or alkaline. Cultures are usually grown either as single layers of cells on a glass or plastic surface or as a suspension in a liquid or semisolid medium.
To initiate a culture, a tiny sample of the tissue is dispersed on or in the medium, and the flask, tube, or plate containing the culture is then incubated, usually at a temperature close to that of the tissue’s normal environment. Sterile conditions are maintained to prevent contamination with Microorganisms. Cultures are sometimes started from single cells, resulting in the production of uniform biological populations called clones. Single cells typically give rise to colonies within 10 to 14 days of being placed under culture conditions.
Cloning
Cloning, the process of generating a genetically identical copy of a cell or an organism. Cloning happens all the time in nature—for example, when a cell replicates itself asexually without any genetic alteration or recombination. Prokaryotic organisms (organisms lacking a cell nucleus) such as bacteria create genetically identical duplicates of themselves using binary fission or budding. In eukaryotic organisms (organisms possessing a cell nucleus) such as humans, all the cells that undergo mitosis, such as skin cells and cells lining the gastrointestinal tract, are clones; the only exceptions are gametes (eggs and sperm), which undergo meiosis and genetic recombination.
In biomedical research, cloning is broadly defined to mean the duplication of any kind of biological material for scientific study, such as a piece of DNA or an individual cell. For example, segments of DNA are replicated exponentially by a process known as polymerase chain reaction, or PCR, a technique that is used widely in basic biological research. The type of cloning that is the focus of much ethical controversy involves the generation of cloned embryos, particularly those of humans, which are genetically identical to the organisms from which they are derived, and the subsequent use of these embryos for research, therapeutic, or reproductive purposes.
Early Cloning Experiments
Reproductive cloning was originally carried out by artificial “twinning,” or embryo splitting, which was first performed on a salamander embryo in the early 1900s by German embryologist Hans Spemann. Later, Spemann, who was awarded the Nobel Prize for Physiology or Medicine (1935) for his research on embryonic development, theorized about another cloning procedure known as nuclear transfer. This procedure was performed in 1952 by American scientists Robert W. Briggs and Thomas J. King, who used DNA from embryonic cells of the frog Rana pipiens to generate cloned tadpoles. In 1958 British biologist John Bertrand Gurdon successfully carried out nuclear transfer using DNA from adult intestinal cells of African clawed frogs (Xenopus laevis). Gurdon was awarded a share of the 2012 Nobel Prize in Physiology or Medicine for this breakthrough.
Advancements in the field of molecular biology led to the development of techniques that allowed scientists to manipulate cells and to detect chemical markers that signal changes within cells. With the advent of recombinant DNA technology in the 1970s, it became possible for scientists to create transgenic clones—clones with genomes containing pieces of DNA from other organisms. Beginning in the 1980s mammals such as sheep were cloned from early and partially differentiated embryonic cells. In 1996 British developmental biologist Ian Wilmut generated a cloned sheep, named Dolly, by means of nuclear transfer involving an enucleated embryo and a differentiated cell nucleus. This technique, which was later refined and became known as somatic cell nuclear transfer (SCNT), represented an extraordinary advance in the science of cloning, because it resulted in the creation of a genetically identical clone of an already grown sheep. It also indicated that it was possible for the DNA in differentiated somatic (body) cells to revert to an undifferentiated embryonic stage, thereby reestablishing pluripotency—the potential of an embryonic cell to grow into any one of the numerous different types of mature body cells that make up a complete organism. The realization that the DNA of somatic cells could be reprogrammed to a pluripotent state significantly impacted research into therapeutic cloning and the development of stem cell therapies.
Soon after the generation of Dolly, a number of other animals were cloned by SCNT, including pigs, goats, rats, mice, dogs, horses, and mules. Despite those successes, the birth of a viable SCNT primate clone would not come to fruition until 2018, and scientists used other cloning processes in the meantime. In 2001 a team of scientists cloned a rhesus monkey through a process called embryonic cell nuclear transfer, which is similar to SCNT except that it uses DNA from an undifferentiated embryo. In 2007 macaque monkey embryos were cloned by SCNT, but those clones lived only to the blastocyst stage of embryonic development. It was more than 10 years later, after improvements to SCNT had been made, that scientists announced the live birth of two clones of the crab-eating macaque (Macaca fascicularis), the first primate clones using the SCNT process. (SCNT has been carried out with very limited success in humans, in part because of problems with human egg cells resulting from the mother’s age and environmental factors.)
Reproductive Cloning Reproductive
cloning involves the implantation of a cloned embryo into a real or an artificial uterus. The embryo develops into a fetus that is then carried to term. Reproductive cloning experiments were performed for more than 40 years through the process of embryo splitting, in which a single early-stage two-cell embryo is manually divided into two individual cells and then grows as two identical embryos. Reproductive cloning techniques underwent significant change in the 1990s, following the birth of Dolly, who was generated through the process of SCNT. This process entails the removal of the entire nucleus from a somatic (body) cell of an organism, followed by insertion of the nucleus into an egg cell that has had its own nucleus removed (enucleation). Once the somatic nucleus is inside the egg, the egg is stimulated with a mild electrical current and begins dividing. Thus, a cloned embryo, essentially an embryo of an identical twin of the original organism, is created. The SCNT process has undergone significant refinement since the 1990s, and procedures have been developed to prevent damage to eggs during nuclear extraction and somatic cell nuclear insertion. For example, the use of polarized Light to visualize an egg cell’s nucleus facilitates the extraction of the nucleus from the egg, resulting in a healthy, viable egg and thereby increasing the success rate of SCNT.
Therapeutic Cloning
Therapeutic cloning is intended to use cloned embryos for the purpose of extracting stem cells from them, without ever implanting the embryos in a womb. Therapeutic cloning enables the cultivation of stem cells that are genetically identical to a patient. The stem cells could be stimulated to differentiate into any of the more than 200 cell types in the human body. The differentiated cells then could be transplanted into the patient to replace diseased or damaged cells without the risk of rejection by the immune system. These cells could be used to treat a variety of conditions, including Alzheimer disease, Parkinson disease, diabetes mellitus, stroke, and spinal cord injury. In addition, stem cells could be used for in vitro (laboratory) studies of normal and abnormal embryo development or for testing drugs to see if they are toxic or cause birth defects.,
Tissue culture is a technique used to grow cells and Tissues in a laboratory. It is a valuable tool for research, as it allows scientists to study cells and tissues in a controlled environment. Tissue culture can also be used to produce cells and tissues for medical purposes, such as organ transplantation.
There are two main types of tissue culture: cell culture and organ culture. Cell culture involves growing cells in a liquid medium, while organ culture involves growing tissues on a solid surface.
Cell culture is a relatively simple technique. Cells are typically grown in a flask or dish that is filled with a nutrient-rich liquid medium. The medium contains all of the nutrients that the cells need to grow and divide. The cells are then incubated at a specific temperature and pH.
Organ culture is more complex than cell culture. Organs are typically grown on a solid surface, such as a piece of plastic or glass. The surface is coated with a layer of cells that support the growth of the organ. The organ is then incubated at a specific temperature and pH.
Tissue culture has a wide range of applications in research. It is used to study the growth and development of cells and tissues, to test the effects of drugs and chemicals, and to produce cells and tissues for medical purposes.
Tissue culture is also used in agriculture. It is used to produce Plants that are resistant to pests and diseases, and to produce plants that are more nutritious.
Tissue culture is a valuable tool for research and agriculture. It allows scientists to study cells and tissues in a controlled environment, and to produce cells and tissues for medical and agricultural purposes.
Cloning is the process of creating an identical copy of an organism. There are two main types of cloning: reproductive cloning and therapeutic cloning.
Reproductive cloning is the process of creating a genetically identical copy of an entire organism. This is the type of cloning that is used to create cloned animals, such as Dolly the sheep.
Therapeutic cloning is the process of creating a genetically identical copy of a specific cell or tissue. This type of cloning is used to create stem cells, which are cells that can develop into any type of cell in the body.
Stem Cell Research is the study of stem cells. Stem cells are cells that have the ability to develop into any type of cell in the body. They are found in embryos, umbilical cord blood, and adult tissues.
Stem cell research has the potential to revolutionize medicine. Stem cells can be used to create replacement tissues and organs for people with diseases or injuries. They can also be used to study diseases and develop new treatments.
However, stem cell research is controversial. Some people believe that it is unethical to use embryos for research. Others believe that stem cell research could lead to the development of human clones.
Despite the controversy, stem cell research is a promising field of medicine. It has the potential to improve the lives of millions of people.
Genetic engineering is the process of modifying the genes of an organism. This can be done to improve the organism’s traits, or to make it resistant to disease.
Genetic engineering is a powerful tool that has the potential to improve the lives of humans and animals. However, it is also a controversial technology. Some people believe that it is unethical to modify the genes of living organisms. Others worry about the potential risks of genetic engineering, such as the creation of new diseases.
Despite the controversy, genetic engineering is a rapidly growing field. It has the potential to revolutionize agriculture, medicine, and other industries.
Here are some frequently asked questions and short answers about tissue culture:
What is tissue culture?
Tissue culture is a technique used to grow cells, tissues, or organs in a laboratory. It is used for a variety of purposes, including research, drug development, and the production of tissues and organs for transplantation.How does tissue culture work?
Tissue culture begins with the removal of cells or tissues from an organism. The cells or tissues are then placed in a culture medium, which is a nutrient-rich solution that contains salts, sugars, and other compounds that the cells need to grow. The culture medium is typically kept in a sterile environment to prevent contamination.What are the benefits of tissue culture?
Tissue culture has a number of benefits. It allows scientists to grow cells and tissues in a controlled environment, which can be used to study the effects of drugs and other treatments. Tissue culture can also be used to produce tissues and organs for transplantation.What are the risks of tissue culture?
Tissue culture also has some risks. One risk is that the cells or tissues may become contaminated with bacteria or viruses. Another risk is that the cells or tissues may mutate and become cancerous.What are the ethical issues surrounding tissue culture?
There are a number of ethical issues surrounding tissue culture. One issue is that the use of human cells in tissue culture raises the question of whether it is ethical to use human tissue for research or other purposes. Another issue is that the use of animal cells in tissue culture raises the question of whether it is ethical to use animals for research or other purposes.
Here are some frequently asked questions and short answers about cloning:
What is cloning?
Cloning is the process of creating an identical copy of an organism. It can be done with plants, animals, and even humans.How does cloning work?
Cloning can be done in a number of ways. One way is to take a cell from an organism and remove its nucleus. The nucleus is then inserted into an egg cell that has had its own nucleus removed. The egg cell is then stimulated to divide, and a clone of the original organism is created.What are the benefits of cloning?
Cloning has a number of potential benefits. It could be used to create organs and tissues for transplantation, to produce food, and to preserve endangered species.What are the risks of cloning?
Cloning also has a number of risks. One risk is that the cloned organism may have genetic defects. Another risk is that cloning could be used to create human clones, which could raise ethical concerns.What are the ethical issues surrounding cloning?
There are a number of ethical issues surrounding cloning. One issue is that the creation of human clones could be used to create a new class of people who are considered to be inferior to “normal” people. Another issue is that the creation of human clones could be used to create soldiers or other workers who are obedient and do not question authority.
Which of the following is not a type of tissue culture?
(A) Cell culture
(B) Organ culture
(C) Tissue engineering
(D) CloningWhich of the following is not a benefit of tissue culture?
(A) It can be used to produce large quantities of cells or tissues.
(B) It can be used to study the growth and development of cells and tissues.
(C) It can be used to test the safety of new drugs and therapies.
(D) It can be used to create clones of animals or plants.Which of the following is not a risk of tissue culture?
(A) The cells or tissues may become contaminated with bacteria or viruses.
(B) The cells or tissues may mutate and become cancerous.
(C) The cells or tissues may not be able to survive outside of the laboratory environment.
(D) The cells or tissues may not be able to function properly in the body.Which of the following is not a use of tissue culture?
(A) To produce Vaccines
(B) To produce organs for transplantation
(C) To create clones of animals or plants
(D) To study the effects of drugs and toxins on cellsWhich of the following is not a limitation of tissue culture?
(A) The cells or tissues may not be able to survive outside of the laboratory environment.
(B) The cells or tissues may not be able to function properly in the body.
(C) The cells or tissues may mutate and become cancerous.
(D) The cells or tissues may become contaminated with bacteria or viruses.