There is not, and perhaps never can be, a full transition of male into female, or female into male. The best efforts only result in a mutilation that effectively changes the male to a neuter, or the female to a neuter, and when carried out to its ultimate conclusion. is absolutely irreversible. The individual then will forever remain a neuter.
Some surprising biological tricks can be pulled, but only through great surgical change and tinkering with the hormonal balances, techniques of which there are a great many ways for things to go horribly wrong.
XX = Female. XY = Male. Written in every cell of the body.
Never can be.
What biological tricks? I watched episodes where Jazz.Jennings got a lopitoffame, and on the next episode, he was talking about his “vagina,” and the doctor called it a wound. That is what it is, although that has nothing to do with hormones.