All together, previous work has provided strong evidence for the existence of fluid flow and micrometer-sized grooves in segments of the mammalian female reproductive tract. In mice, outward fluid flows have been observed in the oviduct and uterus ( 3). In the human, scanning electron micrographs of the cervix indicate that longitudinal microgrooves are also present in the cervical lining ( 7). Furthermore, transmission electron micrographs of the bovine cervix showed that the beating of cilia lining the microgrooves is oriented toward the vagina, whereas the sperm are oriented in the opposite direction, indicating that sperm swim against currents created by ciliary beating in the grooves ( 6). Many sperm were seen within microgrooves in histological sections of the bovine cervix ( 6). Microscopic examination of the bovine female reproductive tract show that longitudinally oriented microgrooves line the inner surfaces of the cervix and uterotubal junction ( 5, 6) ( Fig. It is now increasingly clear that biophysical cues within the female reproductive tract, including surface microgrooves ( 1, 2) and fluid flows ( 3, 4), critically regulate sperm cell migration. Human and bovine sperm, for example, must enter the cervix, swim against a gentle fluid flow, and pass through the uterus and narrow uterotubal junction into the oviduct before reaching the egg ( Fig. Furthermore, the results provide previously unidentified directions for the development of in vitro fertilization devices and contraceptives.įor a successful fertilization, mammalian sperm must migrate through various compartments of the female reproductive tract to reach and fertilize oocytes. This work highlights the importance of biophysical cues within the female reproductive tract in the reproductive process and provides insight into coevolution of males and females to promote fertilization while suppressing infection. foetus swims primarily via three anterior flagella and demonstrates much lower attraction to surfaces. foetus specifically, sperm swim using a posterior flagellum and are near-surface swimmers, whereas T. foetus to swim against flow to the distinct motility types of sperm and T. We attribute the differential ability of sperm and T. In contrast, a flagellated sexually transmitted bovine pathogen, Tritrichomonas foetus, is swept downstream under the same conditions. Using a microfluidic model, we demonstrate that a gentle fluid flow and microgrooves, typically found in the female reproductive tract, synergistically facilitate bull sperm migration toward the site of fertilization. Here we show that the biophysical environment of the female reproductive tract critically guides sperm migration, while at the same time preventing the invasion of sexually transmitted pathogens. For many years, fertility studies have focused on biochemical and physiological requirements of sperm. Successful mammalian reproduction requires that sperm migrate through a long and convoluted female reproductive tract before reaching oocytes.
0 kommentar(er)
