Word: sperms
(lookup in dictionary)
(lookup stats)
Dates: all
Sort By: most recent first
(reverse)
Researchers at Newcastle University in England report they have coaxed the first human sperm cells from embryonic stem cells, in a remarkable demonstration of how quickly the field of stem-cell science is moving...
Although the development once again raises the specter of creating humans in a petri dish or custom-designing egg and sperm cells for reproduction, lead author Karim Nayernia says that was not his team's intention. Rather, the experiment was a proof of concept that stem cells can generate any cell in the body - not only the dozens of tissues that make up the human body but also those egg and sperm cells that may give rise to altogether new bodies. "Other cell types don't generate the next generation," says Nayernia, a professor of stem-cell biology at Newcastle...
Nayernia's in vitro-derived sperm, or IVD sperm, are not exactly like naturally occurring sperm, though they do bear four important similarities to the cells created in the testes. They contain half the number of chromosomes of other human cells (somatic cells contain 46 chromosomes, but egg and sperm cells have only 23, since they combine their genetic payloads during fertilization); they possess a head and a tail; they contain proteins essential for activating the egg during fertilization; and they swim, or move as sperm do in seeking out eggs to fertilize...
...outside, however, IVD sperm are not identical to normal sperm. "We think, for normal structure development, sperm needs the testes environment," says Nayernia. It takes 15 to 16 years in the testes before the primordial germ cells that morph into spermatogonia, or a primitive precursor of the germ cells, are able to mature into sperm cells that can successfully fertilize an egg. (See the top 10 medical breakthroughs...
...sperm are not ready for transplantation into human patients - in any case, British law prohibits their transplantation into people - but they may provide valuable clues to the causes of male infertility. Nayernia's group is now working on creating sperm from the skin cells of infertile men (the sperm cells in the current study were generated from embryos discarded by fertility clinics), and by studying the way those sperm develop, researchers may gain insight into the origins of infertility and potential new treatments. Theoretically, for example, if sperm could be created from the cells of a cancer patient...