An overlooked organ may help the ovary function

When an immense curlicue of tissue sitting below the ovaries was discovered more than a century ago, it was pushed aside as unnecessary and erased from biology textbooks. Biologists now are taking a new stare at the structure and its potential scheme.

The rete ovarii seems to communicate with the ovary by directing a circulation of protein-packed fluids via its long, tubular structure into the organ, researchers file March 19 in eLife. The outcomes attain amid contemporary stories suggesting that the “rediscovered” appendage would per chance be responding to the body’s hormonal signals. While peaceful a speculation, the discovering signifies that this advanced structure may play a scheme in fertility and ovarian upkeep.

When the structure was first acknowledged in 1870, it had no glaring cause, so scientists deemed it a functionless remnant of fashion. And it remained almost passed over for over a century, with researchers focusing on parts of the ovary already known to be biologically vital.

It wasn’t until developmental biologist Jennifer McKey, then at Duke University, was imaging mouse ovaries of their entirety that she noticed a odd shape curving at the bottom of the ovary, love a horseshoe. She rooted via outdated literature until she matched her ovarian horseshoe with the long-forgotten rete ovarii.

In a 2024 Scientific Recordsdata paper, McKey, now at the University of Colorado in Aurora, and colleagues analyzed RNA within the rete ovarii to search out out which genes are switched on and off — and if any are linked to ovarian scheme in mice. The researchers discovered a range of genes turned on when estrogen hormones had been at their absolute best. As an instance, a protein linked to egg cell maturation and follicle upkeep was no longer best secreted by the rete ovarii, however furthermore activated alongside increases in estrogen. This signifies that the rete ovarii would per chance be responding to the hormone cycle in strategies which may be principal for fertility, says team member Dilara Anbarci, a developmental biologist at the University of Michigan in Ann Arbor.

New experiments counsel the rete ovarii secretes protein-filled fluid straight to the ovary, serving as a conduit between the upper ovarian atmosphere and the organ. The exercise of a fluid known as dextran, whose molecules are too huge to passively ooze via tissue, the team tracked an energetic trade of fluid via the rete ovarii into the ovary.

That space is packed with blood vessels and nerves, suggesting that the rete may wisely give you the choice to sense knowledge from the body. Anbarci likens the rete ovarii to an antenna: As hormones fluctuate, the rete perks up, tuning in to ovarian signals and secreting proteins in holding with the ovary’s wants.

These experiments narrate “there’s one thing going on,” says developmental biologist Serge Nef of the University of Geneva, who was no longer eager by the work. But “it’s appropriate the starting up of the narrative…. Whatever it's, is it principal for ovarian scheme?” More experiments should be performed to explain that fertility is affected if the rete is eliminated or shut down, and if the rete ovarii functions similarly in humans.

“There’s peaceful so noteworthy we can’t even delivery up to love about female anatomy,” Anbarci says. “I hope this encourages more investigation in reevaluating what we don’t already know in regards to the ovary.”