STUDIES REVEAL TRIGGERS FOR SPERM PRODUCTION.Byline: Denise Mann Medical Tribune News Service Transferring certain sperm cells from one male to another may be the key to immortality in both mice and men, new research suggests. In a study of mice, cells that trigger sperm production, called stem cells stem cells, unspecialized human or animal cells that can produce mature specialized body cells and at the same time replicate themselves. Embryonic stem cells are derived from a blastocyst (the blastula typical of placental mammals; see embryo), which is very young , were frozen for four to 156 days. Once thawed, these cells were able to spur the development of normal sperm when transplanted into the testes testes or testicles Male reproductive organs (see reproductive system). Humans have two oval-shaped testes 1.5–2 in. (4–5 cm) long that produce sperm and androgens (mainly testosterone), contained in a sac (scrotum) behind the penis. of other mice, Pennsylvania researchers report in the June issue of Nature Medicine. This method may one day offer both help and hope for sterile men - including cancer patients facing chemotherapy for whom the toxic exposure can impair sperm production. Freezing these immature sperm cells before the therapy begins for use later on - either transplanting them back into the patient himself or into surrogate testes - is a promising possibility, researchers led by Dr. Ralph L. Brinster Ralph L. Brinster (1932) is an American veterinarian and Richard J. Mellon Professor of Reproductive Physiology at the School of Veterinary Medicine, University of Pennsylvania.[1] Birth and education Ralph L. Brinster was born in 1932 in the United States. , a professor of reproductive physiology at the University of Pennsylvania's School of Veterinary Medicine veterinary medicine, diagnosis and treatment of diseases of animals. An early interest in animal diseases is found in ancient Greek writings on medicine. Veterinary medicine began to achieve the stature of a science with the organization of the first school in the in Philadelphia. As a patient facing death could also have his sperm frozen, Brinster's findings also add fuel to the contentious ethical debate over whose sperm should be frozen and the ramifications ramifications npl → Auswirkungen pl of such immortality. In a related study, Brinster and colleagues were able to successfully transplant rat stem cells to mice. And the sperm cells generated by the mice were rat cells. This finding raises the possibility that sperm transplants can be made across species lines, Brinster reported in the May 30 issue of the journal Nature. Stem cells can be frozen for a substantial length of time, transplanted into another individual and induce sperm production, Brinster explained. ``Freezing immortalizes the most important cell in the body,'' Brinster explained. ``This particular sperm cell divides and contributes genes to the next generation.'' Calling the findings ``interesting, important and exciting,'' Dr. Marc Goldstein, a professor of urology urology Medical specialty dealing with the urinary system and male reproductive organs. It traces its origin to medieval lithologists, itinerant healers who specialized in surgical removal of bladder stones. at New York New York, state, United States New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of Hospital-Cornell Medical Center in New York City New York City: see New York, city. New York City City (pop., 2000: 8,008,278), southeastern New York, at the mouth of the Hudson River. The largest city in the U.S. , said they may have important ramifications for infertile in·fer·tile adj. Not capable of initiating, sustaining, or supporting reproduction. infertile, adj unable to produce offspring. men. ``This work could enable us to determine whether certain types of infertility are due to defective stem cells or due to a defect in the Sertoli cells that nourish and support sperm,'' said Goldstein, who is also the director of the Center for Male Reproductive Medicine and Microsurgery microsurgery or micromanipulation Surgical technique for operating on minute structures, with specialized, tiny precision instruments under observation through a microscope, sometimes equipped with cameras to show the operation on a monitor. at New York Hospital-Cornell Medical Center. ``If we can use an animal as the medium for human or other animal sperm production, there shouldn't be any ethical dilemmas,'' he noted. Transferring such cells from one human to another human in the hopes of provoking sperm production may, however, pose ethical dilemmas identical to those created when a woman donates an egg to another woman. In this scenario, the woman who receives the donor egg carries the child although the egg is not hers, Goldstein explained. Who are appropriate stem-cell donors? Should such donors be anonymous? These difficult questions will arise because the potential that this method will work in humans ``is real,'' Goldstein added. In the mouse-to-mouse study, transferred mice stem cells generated sperm production in 73 percent of the recipient mice testes, Brinster wrote. And in the rat-to-mouse study, the stem cells induced sperm generation in 19 of 20 recipient testes, study author Brinster found. In both studies, the recipient mice essentially serve as test tubes. And in the future, the cells produced in the substitute testes could be used to fertilize a female egg, he predicted. Freezing these immature stem cells is much simpler and more effective than freezing mature sperm or female eggs, wrote Robin Lovell-Badge of the division of developmental genetics at the National Institute for Medical Research The National Institute For Medical Research, commonly abbreviated to NIMR, is a large medical research facility situated in rural Mill Hill, England, on the outskirts of London. in London, England, in an accompanying editorial. If it becomes possible to cultivate stem cells in a test tube, then some men who have low sperm counts also may benefit, Lovell-Badge wrote. ``This technique holds promise for men who are not making any sperm,'' said Nancy Brackett, the director of the male fertility research program at the Miami Project to Cure Paralysis The Miami Project to Cure Paralysis is a research center dedicated to research in the field of paralysis and spinal cord injury, with the eventual object of finding a cure for paralyzing injuries. Based at the Leonard M. in Miami, Fla. ``Mice could be used to generate human stem cells,'' and the sperm produced could be used to fertilize a female egg, she said. ``With the technology of assisted conception, all we need is one to 10 sperm to try and achieve a pregnancy,'' Brackett added. |
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