Background
Since the discovery of sperm attraction to the female gametes in ferns over a century ago (Pfeffer, 1884), sperm chemotaxis has been established in a large variety of species (Miller, 1985). Although sperm chemotaxis is prevalent throughout the Metazoa kingdom, from marine species with external fertilization such as sea urchins and corals, to humans (Cosson, 1990; Eisenbach and Tur-Kaspa, 1994; Miller, 1985), most of the current information on sperm chemotaxis is derived from studies of marine invertebrates, primarily sea urchin and starfish (Kaupp et al., 2006). As a matter of fact, until not too long ago, the dogma was that, in mammals, any guidance of spermatozoa to the oocyte was unnecessary. This was due to the common belief that, following ejaculation into the female genital tract, large numbers of spermatozoa 'race' towards the oocyte and compete to fertilize it. This belief was taken apart when it became clear that only few of the ejaculated spermatozoa — in humans, only ~1 of every million spermatozoa — succeed in entering the oviducts (Fallopian tubes), and when more recent studies showed that mammalian spermatozoa do respond chemotactially (Ralt et al., 1994).
Read more about this topic: Sperm Chemotaxis
Famous quotes containing the word background:
“... every experience in life enriches ones background and should teach valuable lessons.”
—Mary Barnett Gilson (1877?)
“Pilate with his question What is truth? is gladly trotted out these days as an advocate of Christ, so as to arouse the suspicion that everything known and knowable is an illusion and to erect the cross upon that gruesome background of the impossibility of knowledge.”
—Friedrich Nietzsche (18441900)
“In the true sense ones native land, with its background of tradition, early impressions, reminiscences and other things dear to one, is not enough to make sensitive human beings feel at home.”
—Emma Goldman (18691940)