Quote from: Jayne01 on August 18, 2015, 05:15:18 PM
I was wondering how hormones work. When someone is transitioning, MTF for example, they take female hormones to be and feel more female. Wouldn't the opposite be true with male hormones? I mean, if you took male hormones, wouldn't that make you feel more male, hence match your physical body? That sounds like a better solution to me. It would avoid all the problems of acceptance with family, friends and society in general.
Basically, the way hormones work is that they bind to and activate a receptor molecule, and the combined hormone/receptor complex is then transported into the cell's nucleus, where it acts as a kind of "master switch" for turning on particular sets of genes. The two main types of hormones we're interested in are estrogens and androgens. Estrogens (the main one being estradiol) switch on the genes responsible for the day to day running of a female body, whereas androgens (testosterone and DHT) switch on an equivalent set of genes, except the male version of them. Basically, estradiol tells the cells throughout your body that they're part of a female body, and to do the female version of all the things they do, whereas testosterone tells the cells throughout your body that they're part of a male body and to do the same sort of things, except the male version of them. Whether you have a Y chromosome or not doesn't make any difference at all except in your germ cells (testicles or ovaries), where it drives the formation of testicular tissue. All the other cells throughout your body are effectively gender neutral, and take their cue as to whether to act male or female from whatever hormones are present.
That's what happens in adulthood. In an unborn baby, things work slightly differently. Again, hormones are what tells the cells throughout your body whether they're part of a male or female body, except rather than controlling just the day to day running of that body, they're directing all the sex-specific growth and development that's taking place. As an adult, changes to your hormones have mainly temporary effects, whereas in an unborn baby, the effects are permanent.
For example, just by injecting pregnant lab animals with testosterone, you can cause all their female fetuses to develop as if they were male, and if you start early enough in the pregnancy, you can produce genetically female babies who look just like males. By waiting until a bit later in the pregnancy, you can also produce female animals that look like normal females, except their behaviour is male. As adults, they'll attempt to mate with other females and otherwise behave like they were male, despite having a female body.
That's an important clue as to how ->-bleeped-<- can arise. Basically, all it needs is for something to go wrong with your hormones during your prenatal development, except after the critical period for genital development has finished (which, in humans, is the first trimester). Brain development is ongoing throughout the pregnancy, so you can have had substantial cross-sex brain development take place, even though you look no different from someone else of your biological sex. If this has happened to you, the gender differences are built into the actual structure of your brain, and, as an adult, there's absolutely nothing you can do to change what's there. You can alter your body to better fit in with how you identify though, and take hormones that are a better match for the needs of your brain than the ones your body is producing.
Another difference between adults and unborn babies in the way hormones act, is that, in adults, estradiol needs to be there in order to get your cells behaving in a female way. In an unborn baby, high levels of testosterone will cause male development, but if the testosterone isn't there, a fetus will develop as female by default. The fetus doesn't need ovaries and to be producing estradiol in order to develop as female. If there is testosterone present and able to do its job, development occurs as male, otherwise it occurs as female instead. This is something that's been shown in numerous experiments on animals, and there's a condition called Complete Androgen Insensitivity Syndrome which proves the same applies in human beings too. This is quite important for understanding how MTF ->-bleeped-<- arises. Basically, all it needs is for something to happen to suppress your testosterone production during the second and/or third trimester, for instance exposure to a hormone or other chemical that interferes with testosterone production. It doesn't necessarily have to involve an estrogen.
Something I've been trying to point out to people for a while now, is that, for decades, doctors have been giving pregnant women hormones and other drugs that can interfere with testosterone production, as part of treatment for preventing miscarriages and for various other medical reasons. In the 1960s and 70s, large numbers of pregnant women were also given androgenizing progestins, hormones that turned out to be able to mimic the effects of testosterone in female fetuses. I think it must certainly be an important cause of ->-bleeped-<-, and may well be the main thing causing it.
