Madison, Wis. - A Wisconsin Planned Parenthood clinic in 2010 provided heart and brain tissues from aborted fetuses to University of Wisconsin-Madison researchers for studies aimed at understanding the growth of babies with and without birth defects.

Anti-abortion activists released documents on the research at UW-Madison as they try to salvage a bill to prohibit this sort of tissue transfer before the close of the Wisconsin Legislature's session.

UW-Madison officials have already acknowledged doing this kind of biomedical research, but the documents make clear in addition that Planned Parenthood clinics in the state formerly helped to furnish some tissues involved.

Both UW and Planned Parenthood of Wisconsin officials said that there was no reimbursement for the tissues, that the mothers agreed to the tissue use and that the university is no longer receiving tissues from these state clinics.

The studies provide insight into the moral argument at the heart of the legislation, known as AB 305.

Supporters say the bill would protect against profiteering from, and an improper reliance on, the remains of fetuses, while opponents say there is no profiteering and there are humane reasons to use tissues for bettering the health of all, including the unborn.

UW-Madison spokeswoman Meredith McGlone said the studies seek in part to understand why fetuses with an abnormal number of chromosomes don't grow normally, which can lead to Down syndrome and other medical challenges that have no treatment.

"We currently don't understand why these fetuses don't grow normally," McGlone said. "These chromosomal abnormalities lead some families to seek abortion. Many of these fetuses survive after birth but continue to suffer harmful effects because of their abnormal growth."

The legislation was highlighted last year after the release of videos that were secretly recorded of Planned Parenthood officials in other states purportedly discussing the cost of providing fetal body parts for medical research with anti-abortion activists posing as tissue buyers.

On Monday a grand jury in Texas indicted two anti-abortion activists involved in making videos, and Planned Parenthood's national arm has filed a lawsuit alleging that activists broke the law to misrepresent the practice in the recordings.

Anti-abortion opponents focused on different aspects of the UW-Madison studies, specifically graphic details of how the hearts and brains were removed from the fetuses, which were aborted at between 10 and 18 weeks for reasons that were not related to the research.

The studies were published in 2014 in the journals Molecular Human Reproduction and Prenatal Diagnosis.

The records on the research were obtained through an open records request by Alliance Defending Freedom, a social conservative group opposed to abortion.

An alliance official said the transfer contradicted previous Planned Parenthood of Wisconsin statements that their clinics in the state don't supply any tissues for research.

"Planned Parenthood has once again demonstrated its willingness to cover up its role in the gruesome baby parts trade," said Matt Bowman, an attorney for the alliance.

Iris Riis, a spokeswoman for Planned Parenthood of Wisconsin, said that what her group said is true - the group's clinics no longer supply the tissues.

"Our opponents are desperately trying everything they can to get this fetal tissue bill to the floor," Riis said. "There is no ongoing research project, and the truth remains that Planned Parenthood does not currently offer tissue donation services to our patients. Our focus is on delivering essential health care to all those who are in need."

Lisa Brunette, a spokeswoman for the UW Health, said a study nurse from the university was on hand in 2010 to provide assistance such as collecting the mothers' consent. That eliminated the need to reimburse Planned Parenthood, she said.

Chelsea Shields, a lobbyist for Wisconsin Right to Life, said the documents showed that Planned Parenthood clinics in the state had participated in the "harvesting of baby body parts."

"It's becoming more apparent that legislative action must be taken to end this practice in Wisconsin," Shields said.