23 Mar 2023 • Sperm-sorting techniques have been tried and offered before, but the new procedure — which separates sperm cells based on weight — appears much more accurate and safe, according to a new study published in PLOS ONE.

How did they do this?

• In the study, more than 1,300 couples underwent a sperm-sorting technique that uses a specific multilayer density gradient, or medium, to allow particles of different sizes to separate themselves based on weight.
• Sperm that contain an X chromosome are slightly heavier than sperm containing a Y chromosome , explained study author Dr. Gianpiero Palermo.
• "We let sperm swim into the dense medium," he said. "It's a very simple concept; the lighter sperm rise to the top while the heavier sperm go toward the bottom."
• Next, researchers proceed to intracytoplasmic sperm injection (ICSI) - The embryo undergoes preimplantation genetic testing to screen for chromosomal abnormalities or sex.
• Of the couples who wanted female offspring, 79% of the tested embryos were female. Of the couples desiring a male, almost 80% of their embryos were male.
• In the study group, “the sperm moved well, and the sorting technique didn't impair sperm in any shape or form," said Palermo. "The health of the children is fine so far, and that is all reassuring.” No developmental delays were seen at 3 years of age.

Density gradients are the standard technique used to sort motile (or moving) heavier sperm from non-motile sperm in the first place, "This study takes it a step further by using a specific multilayer density gradient to further stratify the sperm based on their possession of an X or Y chromosome," researchers explained.

Source: Medical Xpress | Read full story