期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：17
页码：5431-5436
DOI：10.1073/pnas.1500541112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceMammalian females must selectively allow sperm with normal morphology and motility to ascend the reproductive tract while rejecting invasion of pathogens. By using microfluidic modeling, we revealed that microgrooves and gentle fluid flows, two major biophysical characteristics of the female tract, synergistically provide preferential pathways for sperm. In contrast, the sexually transmitted pathogen, Tritrichomonas foetus, is swept away from these pathways. These findings are not only valuable to dairy and beef industries for maximizing fertility and suppressing disease, but also to human medicine, because the morphology and movement of bull sperm closely resemble those of human sperm, and T. foetus closely resembles Trichomonas vaginalis, which infects 170 million people annually worldwide. Successful mammalian reproduction requires that sperm migrate through a long and convoluted female reproductive tract before reaching oocytes. For many years, fertility studies have focused on biochemical and physiological requirements of sperm. 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. 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. In contrast, a flagellated sexually transmitted bovine pathogen, Tritrichomonas foetus, is swept downstream under the same conditions. We attribute the differential ability of sperm and T. foetus to swim against flow to the distinct motility types of sperm and T. foetus; specifically, sperm swim using a posterior flagellum and are near-surface swimmers, whereas T. foetus swims primarily via three anterior flagella and demonstrates much lower attraction to surfaces. 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. Furthermore, the results provide previously unidentified directions for the development of in vitro fertilization devices and contraceptives.
