Sentences with phrase «number of egg cells»

Unlike sperm cells, which are replenished throughout a man's lifetime, women have a finite number of egg cells.

Yet only a small number of egg cells are produced by the female body, so they are the limiting factor in many aspects of reproductive science.

Not exact matches

The initial single cell of the egg undergoes a number of cell divisions to produce a mass of similar cells.

The «Puffle» cones are crafted from gai daan jai, which translates to «little eggs,» — a fluffy, eggy waffle with semi-spherical cells — with a number of English interpretations (bubble waffles, eggettes, and Hong Kong cakes, just to name a few).

If you are having a girl, her ovaries now contain primitive egg cells; about six million (approximately six times the number she'll have at the time of birth).

Asexual whiptails have a special trick for making spermless reproduction work: The egg cells in other animals first double their choromosomes once and then divide twice, leaving them as haploid cells, with half the normal number of genetic material.

But the whiptails» egg cells first double their chromosomes twice and then divide twice, leaving them with the normal number of chromosomes and rendering a sperm cell unnecessary.

Combining an egg's genetic leftovers with donor cells may be a way to double the number of eggs available for IVF in women whose ovarian reserve is running low

They made these clones by a process called automatic parthenogenesis: The egg is formed normally (with half the species» usual number of chromosomes), then fertilized by the «polar body,» a cell that is created during oogenesis and contains the same gene copies as the egg, resulting in the shark having half the genetic variation of its mother.

While BPA did not affect the number of eggs retrieved, «it's worrisome that any compound could decrease productivity of the ovarian cells,» said Dr. Fred Licciardi, a specialist in reproductive medicine and surgery at the New York University Fertility Center who was not involved in the study.

During the formation of eggs and sperm, the cell's chromosomes must pair up and part in an elaborate sequence that results in sex cells with exactly half the number of chromosomes as the parent cell.

However, this method raises the following problem: in every nuclear transfer, a small number of defective mitochondria are transferred into the healthy egg cell.

The researchers then confirmed that the number of singly paired chromosomes — also called univalents — was higher in older mouse and even human egg cells, indicating that age - related segregation errors could be tracked back to increased numbers of prematurely separated chromosome pairs.

But the discovery of vast numbers of immature eggs dying in the ovaries of mice led Tilly's team to find what they claim are hidden ovarian stem cells that can sprout new eggs to replace

This made the resulting egg cells more likely to have the wrong number of chromosomes (Current Biology, doi.org/b46s).

They found that women with the lowest number of eggs also had the shortest telomeres — the chromosome caps that wear away as cells age — in their white blood cells.

Some research suggests a small number of stem cells continue making new eggs throughout a woman's life, but we don't know much about these yet.

When a sperm cell meets an egg cell (the oocyte), it burrows through the thick outer rind surrounding the egg (the zona pellucida), enters the internal cytoplasm of the egg (the ooplasm), and locomotes its male DNA — half of the typical number of chromosomes — to the female half within about three to four hours.

But he adds that if human parthenotes routinely contain as many genetic mismatches as the Korean cells, the number of eggs needed to create such a bank could be prohibitively large.

Because the egg - donor mother also supplies to each embryo a small number of mitochondria — tiny energy factories within cells that have some of their own genetic material — this approach even affords lesbian couples an approximation of sexual reproduction.

«The use of nonhuman oocytes for SCNT is currently the only ethically justifiable option given the large numbers of eggs required to derive cloned human stem cell lines,» he said.

SCNT requires a large number of eggs and produces very few stem cell lines.

After an extended number of cell divisions, random segregation of mitochondria may lead to cells containing a majority of mitochondria from the donor egg.

Human tissues exposed to either drug for one week in a dish had reduced numbers of cells that give rise to sperm and eggs, called germ cells, the study found.