You can 3D-print pretty much anything these days. Need a base on the Moon? A robot can 3D-print one for you. How about an entire human heart? Yep, you’re covered. You can even, somewhat anemically, 3D-print cheese into rather pointless structures.

A team led by the Northwestern University of Chicago has set the bar pretty high, though. As revealed in a Nature Communications study, they’ve managed to 3D-print ovary structures for mice.

Printed using a gelatin “ink”, these synthetic ovaries were planted into female mice after they had their actual ovaries removed. Not only were they able to ovulate, but they also managed to give birth to healthy pups that were nursed to full health.

The ovaries, which are also important hormone control centers, continued to keep hormone levels within the mother mice at normal levels. For all intents and purposes, their performance was indistinguishable from the real deal.

Plenty of women have problems conceiving after they’ve suffered from an ailment or disease – particularly cancer – or after they’ve undergone medical treatment that has in some way damaged their ovaries. This type of ovarian harm can also severely impede hormone production, which is particularly risky for girls who are about to go through puberty.

This groundbreaking study shows that at some point in the not-too-distant future, synthetic 3D-printed ovaries may be able to be implanted into women with these issues. Organ donors will no longer be required.

“Using bioengineering, instead of transplanting from a cadaver, to create organ structures that function and restore the health of that tissue for that person, is the holy grail of bioengineering for regenerative medicine,” co-author Teresa Woodruff, a reproductive scientist and director of the Women’s Health Research Institute at Feinberg, said in a statement.

^{Explaining the procedure. NorthwesternU via YouTube}

The ink choice was key here. Gelatin, made from broken-down collagen, is rigid enough to be manipulated during surgery, but porous enough to allow it to properly interact with the mouse’s biology. At a certain temperature, the team found that they could print complex, multi-layered structures with it, and eventually this led them to constructing a synthetic ovary.

Although it required decades of research to be able to 3D-print these ovary scaffolds in the first place, the team uncovered plenty of new information along the way. For instance, it wasn’t known until just now that the precise geometry of the ovary has a huge effect on whether or not the ovarian follicles – the supporting cells that encase an immature egg cell – will become viable within the ovary.

All in all, this study represents a huge leap forward in reproductive science.