The Grapevine

Unusual Sperm Structure Could Cause Infertility, Miscarriages

It was believed, during fertilization the father donates only one centriole. But researchers at the University of Toledo (UT) have discovered a second centriole also comes from the father. The newly identified structure in human sperm may contribute to infertility, miscarriages and birth defects. 

The study titled "A Novel Atypical Sperm Centriole is Functional During Human Fertilization" was published in Nature Communications on June 7.

The father is the sole contributor of what is known as the centriole, an essential cellular structure. Centrioles are required for proper cell division and function. 

A fertilized egg cell (or zygote) needs two centrioles to start life. Previously, experts did not have a complete understanding of how the two centrioles were gained. It has been speculated the sperm provides a single centriole to the egg which would then duplicate itself.

Using super-resolution microscopy, the research team reported the discovery of the "previously elusive centriole" which functioned just like the known centriole. Avidor-Reiss explained it was missed in past research because it had a completely different structure and protein composition compared to its known counterpart.

"This research is significant because abnormalities in the formation and function of the atypical centriole may be the root of infertility of unknown cause in couples who have no treatment options available to them," he said, adding it may also have a role in early pregnancy loss and embryo development defects.

The super-resolution microscopy played a crucial role in identifying it by magnifying proteins at the highest resolution. The small core set of proteins (found in the atypical centriole) is required for the known sperm centriole to form a fully functional centriole after fertilization in the zygote using the egg's proteins, the press release stated.

The entire idea for the study started with a fly, said Lilli Fishman, a Ph.D. candidate from the university who worked on the research. When conducting basic fly research, their attention was drawn to the sperm structure as findings indicated the structure may need a closer look. The research team proceeded to examine the sperm of human beings, flies, beetles, and cattle.

The discovery could help prompt diagnostics and therapeutic strategies for targeting male infertility as well as the embryo defects. 

"We are working with the Urology Department at The University of Toledo Medical Center to study the clinical implications of the atypical centriole to figure out if it's associated with infertility and what kind of infertility," Avidor-Reiss said.