Medical Discovery NewsBridging the World of Medical Discovery and You

Recent Episodes

What Makes a Male


Just how much of the Y chromosome is needed to make a male?

Not much, according to a new study!

We've known for just a couple of decades that only one gene determines gender. Now we also know that it takes just two genes out of the 78 genes on the Y chromosome to actually produce a healthy male... well, for now, male mice.

Still, this has huge implications for humans and infertility in males. It could mean that men with immature sperm can reproduce through in vitro fertilization. In the study, researchers tried exactly that with mice.

They injected immature mouse sperm into mouse eggs. This immature sperm contained two genes from the Y chromosome - the SRY gene, which determines sex, and the Eif2s3y, which produces sperm cell precursors.

In 9% of the cases, the offspring produced grew into normal, healthy male mice that were infertile but could reproduce with help.

Even thought that's well below the 26% success rate when they injected eggs with a Y chromosome, it's still eye-opening.

To try this on humans, scientists would need to tweak the method, since Eif2s3y is not on the Y chromosome. Instead, there's a copy on the X chromosome.

It's possible that by using Eif2s3y, researchers can one day develop precursor sperm cells that mature enough to produce viable offspring. These male children would also have immature sperm cells and would need help reproducing.

This study doesn't render the rest of the Y chromosome useless, though. In fact, those genes are necessary to produce fully viable sperm capable of fertilization.

More Information

Only two genes maketh the man... or mouse
"Being a male is easier than it looks. The defining genetic feature of maleness, the Y chromosome, contains only two genes that are absolutely essential for male function ' at least in mice. The discovery may someday help develop new forms of assisted reproduction for infertile men."

Two Y Genes Can Replace the Entire Y Chromosome for Assisted Reproduction in the Mouse
Original journal article by Dr. Yasuhiro Yamauchi, et al, published in Science
Provides a great deal of information about reproduction and fertility for laymen; sponsored by the American Society for Reproductive Medicine


Medicine is constantly advancing – that is a great thing about life in the 21st century. But it doesn’t just happen. Dedicated biomedical scientists are making discoveries that translate into those new medical advances.

Biomedical science is broad, encompassing everything from social science to microbiology, biochemistry, epidemiology, to structural biology and bioinformatics to name just a few areas. And, it can involve basic fundamental biology, the use of AI and chemistry to clinical studies that evaluate new medicines in patients.

No matter the research focus, the goal is always the same, to advance human health. It may take a few months, a few years or for fundamental science, a few decades. Few people make the connection that biomedical science is medicine and that biomedical scientists are working today on the medicine of tomorrow. Our weekly 500-word newspaper columns and 2-minute radio shows and podcasts provide insights into a broad range of biomedical science topics.

Medical Discovery News is dedicated to explaining discoveries in biomedical research and their promise for the future of medicine.


Alternatively, you can copy and paste the following web address (URL) into iTunes as a new subscription:

You can also search and subscribe to "Medical Discovery News" in the podcast section of iTunes.

See all podcasts and radio stations

The web site and Medical Discovery News radio program (Program) are made possible by The University of Texas Medical Branch at Galveston (UTMB)as a community service and are intended to advance UTMB's mission of providing scholarly teaching, innovative scientific investigation, and state-of-the-art patient care in a learning environment to better the health of society and its commitment to the discovery of new innovative biomedical and health services knowledge leading to increasingly effective and accessible health care for the citizens of Texas.

All information provided on the web site and in the Program is for informational purposes only and is not intended for use as diagnosis or treatment of a health problem or as a substitute for consulting a licensed medical professional. Any information obtained by participating as a web site visitor or program listener is not intended to and should not be considered to constitute medical advice.

Thoughts and opinions expressed on the Program or on the website are those of the authors or guests and do not necessarily reflect the opinions of UTMB. The provision of links to other websites is not to be construed as written or implied sponsorship or endorsement of such websites by UTMB.

Please contact Dr. David Niesel or Dr. Norbert Herzog via email with any concerns, suggestions or comments.

All rights are reserved to information provided on the website or other information sources. No part of these programs can be reproduced stored in a retrieval system or transcribed in any form or by any means for personal or financial gained without the express written permission of Drs. Niesel and Dr. Herzog.