Experiment video showing that weak sperm is blocked before reaching ovum

It is said that about 100 million sperm are released by a single ejaculation, but only one of them can reach fertilized eggs. In order to screen strong spermatozoa that can survive the fierce competition of about one hundred million, female reproductive organs sift spermato variously. Researchers at Cornell University simulated the movement of spermatozoa within the reproductive organs and announced the results of experiments, as an example of which is "body fluid flow and genital structure".

Strictures of a microchannel impose fierce competition to select for highly motile sperm | Science Advances
http://advances.sciencemag.org/content/5/2/eaav2111

Watch these sperm wriggle up a model reproductive tract - The Verge
https://www.theverge.com/2019/2/13/18223734/watch-sperm-model-reproductive-tract-study

It is possible to see from the following movie the appearance of the sperm that is being washed away trying to desperately proceed inside the device.

Strictures of a microchannel impose fierce competition to select for highly motile sperm - YouTube


A research team led by food chemist Alireza Abbaspourrad has developed a device in a microfluidic device that can simulate the movement of sperm in reproductive organs with high accuracy. Microfluidics is a discipline to study the behavior of liquids chemically and physically in the world of 100 nanometers to hundreds of micrometers. With the development of technology, it became possible to produce highly accurate experimental equipment, and "microfluidic device" which passed through a thinner tube than glass to the glass or silicon was also developed, and one of the fields showing momentum in recent years is.

Richard Wheeler (Zephyris)

The research team had previously prepared a mathematical model to predict sperm movement based on microfluidics dynamics. Then, in a microfluidic device provided with a stenosis section of about 40 micrometers (about 0.04 mm), a liquid having a viscosity close to that of a body fluid is caused to flow, and how bovine and human sperm behaves in the microfluidic device I observed it. The actual movement of the sperm swimming around the flow is almost as expected, and the distance which was swept away was somewhat shorter than the simulation. D in the following image is a graph of the distance (vertical axis) where the sperm is flowed (vertical axis) and the speed of the sperm (horizontal axis), and the simulation (blue) and the experiment value (green, red, black) are compared.

The following image shows that spermatoes numbered 1 to 7 trying to pass through the stricture against the flow from left to right within the device through which liquid flows from left to right. The sperm 1 is able to move to the left room, but the 2nd, 4th and 5th have been swept to the right. Swells and folds that make up the flow of body fluids and extremely narrow spaces have become barriers to the selection of strong sperm and it is impossible to reach the eggs unless strong sperm that can pass through the barrier.

Mr. Abbaspourrad told The Verge "More research will be required to confirm that strong sperm produces better embryos.This experiment shows how spermatozoa can be detected by the uterus and fallopian tubes It will observe whether it goes through the junction of the body. "