The Female Reproductive Tract – A Natural Selection Gatekeeper
There was a study recently published in the journal Science Advances that took an exciting look at the female reproductive system and specifically, how it is biologically designed to filter sperm through a series of gates – ultimately weeding out the slowest “swimmers.” While we can marvel out how intricately designed a woman’s anatomy is to accomplish this filtration effect, it isn’t necessarily the most heartening story for couples who are battling infertility or having trouble conceiving a child. But there is encouraging news…
First, while the study essentially correlates the filtered-out sperm with being the “weakest” of the group observed, they really were just the slowest. From a reproductive science perspective, we know that the fastest swimmers aren’t necessarily the “best” quality sperm and there are many factors involved in assessing and determining sperm quality. So even if a man’s swimmers are “slow” and his partner’s reproductive tract doesn’t allow them to pass through its gates, it doesn’t mean they’re bad or worthless. When necessary, even the slower swimmers can be extracted successfully and used during insemination procedures to help couples conceive a child.
For example, we don’t seem to see problems when we bypass these natural selection gates of the female reproductive tract with procedures such as intrauterine insemination (IUI). During this fertility treatment procedure, the sperm is placed directly inside the uterus, effectively bypassing the reproductive tract pathway they would generally attempt to take – to help facilitate the fertilization of an egg. The goal of this procedure is to increase the chances of motile sperm reaching the fallopian tubes, thereby increasing the opportunity to fertilize the egg. IUI can be thought of as a “head start” for sperm and may be a less invasive and less costly option for couples than in vitro fertilization.
Fascinating studies like these help give scientists and physicians further insight into the complicated and fascinating process of human reproduction. They also help us to investigate further and develop ways to help couples facing infertility issues find effective ways to “work around” these processes to achieve their dreams of becoming parents to healthy babies. So, while the slower sperm may not “make it” all the way to the egg, we’ve got ways for the strong to survive and thrive.