All fertility stories

Chimps in wild appear not to regularly experience menopause

404132862 — Thu, 13 Dec 2007 11:05:03 -0500

A pioneering study of wild chimpanzees has found that these close human relatives do not routinely experience menopause, rebutting previous studies of captive individuals which had postulated that female chimpanzees reach reproductive senescence at 35 to 40 years of age.

Together with recent data from wild gorillas and orangutans, the finding -- described this week in the journal Current Biology -- suggests that human females are rare or even unique among primates in experiencing a lengthy post-reproductive lifespan.

How a sperm wags its tail

70652986 — Mon, 26 Mar 2007 06:24:46 -0400

The electric activity that spurs sperm to make a final dash to, then into, a female egg has been measured for the first time. To produce this all-important fertility sprint, sperm tails must switch from an easy, symmetrical beating to a frenetic whiplike lashing. This switching slows down sperm cells but gives them the extra force they need to penetrate an egg's protective coating.

Harvard, MGH researchers track egg cell production to marrow

50443248 — Fri, 20 Jul 2007 15:51:26 -0400

Harvard researchers have found new evidence that female mammals can produce egg cells throughout life and have traced their production out of the ovary and into the bone marrow in findings that could both reshape science's understanding of female reproduction and provide new avenues for treatment of infertility.
In a series of experiments on sterile female mice, researchers from Massachusetts General Hospital (MGH), a Harvard teaching hospital, were able to restore egg production by transplanting bone marrow from fertile mice. The researchers believe that egg stem cells in the donor bone marrow established themselves in the sterile mice and began producing egg cells, also called oocytes.

Appetite hormone restores fertility

70652986 — Mon, 26 Mar 2007 05:35:50 -0400

A hormone called leptin has been trumpeted as an appetite suppressor and a possible treatment for obesity. New research shows that "a clear connection also exists between fat, or energy storage, and the ability to reproduce," says Corrine Welt, an assistant professor of medicine who works at Massachusetts General Hospital, a Harvard affiliate. The women whose fertility was boosted by leptin injections had stopped menstruating as a result of losing an abnormal amount of fat, mainly by overexercising. In their 20s and early 30s, they pared themselves down to carrying about 40 percent less fat than is average for women their age. Such loss of menses, or amenorrhea, is also associated with abnormal levels of thyroid hormones and a loss of bone mass, which can lead to brittle, easily fractured bones. The findings thus raise the possibilities of new treatments for exercise-induced bone loss and for eating disorders, as well as for certain cases of infertility.

Formin gene may explain a common cause of female infertility

70652986 — Mon, 26 Mar 2007 05:28:02 -0400

Harvard Medical School researchers Philip Leder and Benjamin Leader have discovered that oocytes from female mice without the formin gene Fmn2 cannot correctly position the metaphase I DNA-spindle. This produces daughter cells with an abnormal number of chromosomes, the leading cause of female infertility, birth defects, and embryo loss. Genes of the formin family, including Fmn2, are expressed in almost all organisms. The discovery may help explain recurrent pregnancy loss, a condition that affects millions of women throughout the world.

Sorting good eggs from bad ones

70652986 — Mon, 26 Mar 2007 05:13:04 -0400

An oocyte is an immature egg cell in the ovaries. Before a woman is born, her ovaries will contain about five million eggs. At birth, about three million of those egg cells die -- apparently by committing suicide. This fact of nature has long puzzled scientists. Now, Harvard researchers working at the Center for Blood Research have uncovered a critical clue that may lead to a greater understanding of infertility and miscarriage. Oocytes are killed by proteins called caspases. Studies in worms have suggested that the caspases are triggered by a unique set of signals in oocytes. But up until now no one has been able to discover those molecular signals. Rosa Navarro, Keith Blackwell, and their colleagues recently identified one such signal -- a defect in a protein needed for processing RNA. In worms lacking the protein, oocytes underwent mass suicide. The findings in worm oocytes could shed light on questions of human concern, such as infertility. "I think we're plugging into something that's involved with what makes a good oocyte," Blackwell said. Being able to distinguish good oocytes from bad could yield information about the potential for birth defects, miscarriages, and infertility.

Cell death in eggs traced to smoking

70652986 — Mon, 26 Mar 2007 05:13:07 -0400

A woman is born with just so many egg cells, called oocytes. When she begins ovulating, she has about 400. Even though that may seem like a lot, considering the few that would ever be fertilized, scientists have found that loss of oocytes influences a woman's health. Early loss of oocytes leads to early menopause and infertility. A study by researcher Jonathan Tilly, Harvard Medical School associate professor of obstetrics, gynecology and reproductive biology at Massachusetts General Hospital, has found that chemicals in cigarette smoke and environmental pollutants can trigger egg loss. "There's a longstanding relationship between smoking and early menopause," Tilly said.