Sperm quality control
Male fertility can be quickly determined using a special chip
Polina Gershberg, Naked Science
The standard tests of male fertility used today are usually based on measuring the motility and concentration of sperm in an ejaculate sample. But there are other factors that affect the likelihood of successfully having a child. For example, spermatozoa may have problems with chemotaxis.
Chemotaxis is the movement of microorganisms, as well as living mobile cells, for example, leukocytes or spermatozoa, caused by the influence of chemicals. Cells sense direction by increasing or decreasing the concentration of a chemical. To successfully fertilize an egg, male seed cells must follow a chemical trail leading them to the target. If this process is disrupted, then the couple may try to conceive for a long time, having otherwise excellent test results, and not understand what the problem is.
Researchers who published their work in the journal Analytical Chemistry (Berendsen et al., Flow-Free Microfluidic Device for Quantifying Chemotaxis in Spermatozoa) have developed a microfluidic chip that helps to quickly assess this chemotactic response of cells, which allows to get a more complete picture of male fertility.
As previous studies have shown, in many mammalian species, chemotaxis allows the sperm to "grope", due to the difference in progesterone concentrations, the way through the fallopian tube to the egg. This hormone is present in high concentrations in the fluid that surrounds the egg.
Previously, microfluidic devices were used in experiments: plastic or hydrogel chips with tiny channels through which liquids pass under strict control. Such devices have various limitations, such as the need for micro-pumps to control fluid flow, which can affect sperm motility.
The authors of the new work have developed a microfluidic chip the size of a postage stamp. Their task was to create a microfluidic device without a pump that could quickly detect small differences in the chemotactic behavior of spermatozoa. It is such a chip that would make it possible to use the technique in real testing.
The new chip, made of agarose-gelatin material, contains various channels and side chambers. The device is currently being tested at the preclinical testing stage. The researchers created a gradient of progesterone concentration in the device from left to right and saw that more boar sperm added to the device got into the right side chambers (high progesterone level) than into the left (low progesterone level), which indicates chemotactic movement.
The diagram shows that more sperm tend to the chambers on the side where the concentration of progesterone is higher /© Analytical Chemistry 2019.
Scientists note that, in addition to direct use during fertility testing in the way that has been developed now, the device can help investigate the contribution of other substances to the mechanism that controls sperm activity.
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