Yep, Gyno, GP, Psychatrist, and an Endro can all perscribe HRT -- basically, anyone who has the medical licence to do so.
I got mine through my GP. It was almost a year before I went and saw the Endro (only one Endro will take Trans patients in town, and the wait is long, and you usually need to see the doc at the GID clinic first, which is a year wait).
The Endro was optional for me, but I thought I'd see him for curiosity sake. I saw him, I flashed him my breast, he stared and drooled for a bit, and then said that I'm an amazing young woman and he's pretty sure my GP knows what he's doing. The Endro here isn't always that bright, he's very bad at testing your levels (he doesn't think that they need to be tested) and he usually prescribes birth control (yeah, I've one friend who's got a low dose of spiro, birth control, and hasn't ever had a blood test from this guy, and she's been seeing him for a year and is going for GRS... sadly, she's gotten black market hormones because she couldn't find a competent doctor). And then, when you ask him about hormones, he gives everyone different and conflicting information. So, yeah, after checking him out myself (I was in the wait list forever anyway), and after hearing of the multiple complains from other trans patients and knowing what wacko combos they were put on without even bothering to order any blood tests, I figured my I'd just stick with my GP (who is learning, and follows the Vancouver GID program outlines, and constantly monitors my levels... and, on top of that he's going to different trans-health conferences, and doing a lot for other trans people... pretty cool doc, plus he also is a musician). I wouldn't say he's perfect, but no body is, but he really tries and really listens and makes sure you are healthy and getting your tests done regularly.
So, moral of the story -- any one who can legally prescribe meds and give out HRT, but that doesn't mean they know what they are doing or are that great. If possible, check out a few options. I tried a couple of doctors. I tried one doc, who was nuts, I tried a walk in doctor what just handed me what ever I wanted without a blood test or a letter from a therapist, one doctor who thought that I should just "accept the body that 'God' gave me," and then, finally, a doctor who tested my blood, adjusts my medication to the best of his knowledge, and is actually willing to listen and learn, and open his doors to the trans community because he knows how hard it is to get a doctor in Calgary, especially one that won't shut the door on you. Yes, we have a shortage of doctors -- few people have a family doctor and most see walk in doctors that are so busy some will hand out meds like candy, and the doctor changes every week. Or you get doctors that just don't want you as a patient, or crazy doctors that have no clue what they are doing and decide your dosage based on how they feel. That's what happens when you live in a city that's in a boom and has too many people and is growing too fast for anyone to keep up.
--Natalie