Interaction between stem cells and their niches key to differentiation
...uctive system that can proliferate and mature into sperm and eggs. While it is has been appreciated that t...hown to be the key gene involved in development of sperm cells. In humans, Lin's team discovered in 2002 that overexpression of the hiwi gene, a piwi-like ge...Parents' attitudes to sperm donation still some concerns about being open
... trend in society to be more open about the use of sperm donors. However, they indicate that not all parent...me compulsory last June in the Netherlands for all sperm donors to be identified. The Fertility Center at Leiden University Hospital has run a double-track s...Cricket's finicky mating behavior boosts biodiversity
... or capsule, to be transferred contains the actual sperm cells that impregnate the female. As a species begins to split into two separate species, says Mendelson, "the songs appear to be the first characteristic that changes." During the early part of the speciation process, says Mendelson, crickets of the...Field-cricket study shows that when it comes to competition, sperm quality matters
By studying the relationship between sperm viability and reproductive success in a cricket sp...e come closer to understanding the contribution of sperm quality to reproductive success, at least in insects. A major advance in evolutionary theory has bee...Sexual cooperation: Mating increases longevity in ant queens
...rrespective of whether males could transfer viable sperm or had been sterilized prior to mating. It remain...a short period early in life and store and use the sperm of their mate for the rest of their lives. Sexual offspring are only produced after several months o...HHMI professor, 138 undergraduates identify essential genes in eye formation
... Recombination normally occurs when organisms make sperm and eggs but does not occur when an organism's other cells divide, the process of mitosis. What makes mitotic recombination possible in Banerjee's flies is the presence of flippase, an enzyme genetically engineered into the flies that is expressed on...Scientists will discuss remarkable advances in whale research at the annual meeting of AAAS
...ce, who will describe how toxicological studies of sperm whales are improving our understanding of ocean pollution; and Craig Smith of the University of Hawaii, who will describe new studies showing how dead whales support invertebrate life on the seafloor. ''If filmmaker Jacques Cousteau could climb out o......as found and collected skin samples from over 1100 sperm whales from some of the most remote ocean regions of the globe. He chose to sample sperm whales because they ranged worldwide and are whale icons thanks to Melvilles tale of Moby Dick, the......of genetic reshuffling that goes on during egg and sperm production differs between males and females in mo...t differences in selection among gametes - eggs or sperm - might help account for recombination differences between the sexes. By analyzing a dataset of 107...Researchers find three major beetle groups coming up one testis short
... beetles are similarly providing other things than sperm to the females. But it's a chicken and egg question. We don't know what came first. Was the testis lost first, leaving more space for the accessory glands to grow? Or did the testis lose out to make way for a larger accessory gland? That's a subject ...Protein delivers selenium for normal sperm development
...the body. Dietary selenium is essential for normal sperm development and male fertility. Selenoprotein P, o...nd that the mutant male mice lacking SEPP1 develop sperm with defective tails, similar to the sperm produced by unaltered male mice fed a low-selenium diet. ...... of those organs to produce and maintain levels of sperm needed for fertility in mice, according to researc...turing germ cells in the testis." The animals lack sperm because of defects inherent to the cells that serve as progenitors of sperm - cells that are usually...Mice with defective sperm offer clues to infertility in men
...r developing a reversible male contraceptive. "The sperm from these mice have problems similar to many defects seen in human sperm that contribute to infertility," says Hermann Steller, Ph.D., head of the Strang Laboratory of Apopt...New findings in taste and smell research
... Sperm Are Attracted by Chemicals -- Mechanisms of sperm navigation in turbulent flow. Human pheromone re...cnrs.fr SPERM: Chemical communication between sperm and egg is widely prevalent among taxa with divergent reproductive strategies. Sperm chemoattractant...Of mice and men's (and women's) contraceptives
...ers to the group of cells that give rise to either sperm or eggs in animals, as opposed to all other cell t...proteins are critical for the production of normal sperm and also are unique to germ cells. "When trying to develop a new contraceptive, it's hard because w...To sea or not to sea: When it comes to salmon sex, size sometimes doesn't matter
...r" as the full-size males that are releasing their sperm in a competitive frenzy as the female deposits her eggs. And the tiny male has avoided the harrowing journey taken by most salmon to the ocean and back, bypassing hazards such as dams, sharks and fishermen. "In some species, all or a fraction of t...With a complement, the sperm gets the egg
When a sperm fuses with an egg, a specific reaction takes place...plement activation occurs on the surface of viable sperm upon exposure to follicular fluid. The data suggest that this localized complement activation aids ...Royal Society study on adaptability of fish to warming oceans
...of rival males over the fertilization of ova. Such sperm competition accounts for many aspects of reproduct...thin litters, together with an association between sperm competition intensity and the size of the seminal fluid-producing accessory reproductive organs (sem...How the environment could be damaging men's reproductive health
...onmental pollutants could be changing the ratio of sperm carrying the X or Y (sex determining) chromosomes ...erm, leading to a slight increase in the number of sperm bearing the Y chromosome Aleksander Giwercman, professor of andrology at the Scanian Andrology Cent......are in contrast to those who feel that the site of sperm entry determines the orientation of the future body axes. "It would now make sense to base our future experiments on the premise that the mammalian egg neither has nor requires predetermination for successful development," explains Dr. Hiiragi....