Athletics' governing body the IAAF has told the World Medical Association it "strongly disagrees" with its call for doctors to refuse to help intersex athletes lower their testosterone so they can compete in female races.
The IAAF claimed a landmark legal victory last week when the Court of Arbitration for Sport rejected an appeal from South Africa's double Olympic 800 metres champion Caster Semenya against the federation's 'eligibility regulations for the female classification'.
The court's majority verdict means athletes who are legally female but have one of a number of specified genetic conditions - collectively known as differences of sex develop - must reduce the testosterone in their blood stream to a level closer to the typical female range.
Athletes subject to the limit have XY male chromosomes, not XX female chromosomes, internal testes, no ovaries, testosterone in the typical male range, and androgen receptors that mean their bodies can use the hormone to develop stronger bones and muscles and have higher counts of haemoglobin, the blood protein that transports oxygen.
Any athlete who meets this description, and wants to compete internationally, must provide a blood test by May 8 to show their testosterone is below the limit, although these rules only apply to track events between 400 metres and a mile.
The IAAF's attempts to regulate this complicated and contentious area have been steeped in controversy since Semenya stormed to fame at the 2009 World Championships in Berlin, where she claimed the first of her three world titles but was also subjected to international scrutiny about her gender.
The days since the CAS verdict was announced have seen a furious response from her supporters, while the IAAF has remained largely silent.
An example of the reaction to the ruling was last week's "advice" from WMA president Dr Leonid Eidelman to the organisation's 114 member associations, which include the British Medical Association.
In a statement published on its website, Dr Eidelman said: "We have strong reservations about the ethical validity of these regulations.
"They are based on weak evidence from a single study, which is currently being widely debated by the scientific community. They are also contrary to a number of key WMA ethical statements and declarations, and as such we are calling for their immediate withdrawal."
This was the second time it had called on doctors to play no part in implementing the IAAF rules and its "reiteration" was widely shared by Semenya's supporters.
Perhaps conscious it was losing the PR battle, the IAAF has now broken its silence by publishing detailed notes on the regulations, which include answers to the 12 most common questions it has received from journalists, and an open letter to Dr Eidelman.
That letter starts by restating the basis for the regulations and to whom they apply but quickly gets to the nub of the matter.
Dismissing the claim the regulations are based "on a single study", the IAAF says they are supported by "many scientific publications and observations from the field during the last 15 years" and CAS has "accepted the validity of this evidence".
On the issue of whether doctors should intervene with treatment for a condition that does not involve an illness, the IAAF "respectfully reminds" the WMA that international guidelines for differences of sex development call for "extensive investigation" to "clarify" the individual's gender.
This could then lead, the IAAF says, to a "suitable form of treatment" to reduce testosterone, which may include removing the male gonads as there is often a heightened risk of cancer.
For intersex individuals with XY chromosomes, the federation claims the reduction of testosterone, usually with contraceptive pills, is "the recognised standard of care" and is "gender-affirming".
The letter, which is signed by the chair of the IAAF's board of medical experts on differences of sex development, Professor Angelica Linden Hirschberg, the University of Michigan's Professor Richard Auchus and IAAF health and science department director Dr Stephane Bermon, then points out that while CAS agreed the regulations are "discriminatory" it also believes they are "proportionate".
"Therefore, the IAAF strongly disagrees with the WMA reservations about the ethical validity of the IAAF regulations," it said.
"We respectfully request that the WMA circulates this response to all its members so they are aware of this information and can follow the recognised standard of care for 46,XY DSD athletes with a female gender identity."
Semenya has said nothing publicly since telling reporters at the season's first Diamond League meeting in Doha on Friday that she has no intention of taking drugs to reduce her testosterone or step up to the 5,000 metres, which is not yet one of the "restricted events".
As of last Wednesday, she had 30 days to decide if she wanted to take her fight to the Swiss federal courts but there has been no word on this as yet.
That said, her most recent Twitter post was a picture of a clenched fist with the word "Resist" underneath.