 Humoral immune response is actually mediated by B lymphocytes. So these are the guys that are primarily involved in the humoral immune response. What we'll see is, once again, just like we tried to separate out innate immunity and acquired immunity, and we're learning that, yeah, no, that's not happening. Separating out humoral immunity and cell-mediated immunity, there's lots of overlap, but in general, the humoral immune response is dealing with B lymphocytes, whereas the cell-mediated response is dealing with T lymphocytes. And we're going to look at where these cells are born, where they go to school, and what kind of receptors they have. And we've talked about the, like we keep saying that's super specific, like crazy specific, and the receptor is why we say that. Both of these guys are born in the bone marrow. B lymphocytes also go to school in the bone marrow. B for bone marrow for school. T lymphocytes go to school in the thymus. And just for perspective, thymus is an endocrine gland that's located superior to the heart. It's something that usually gets removed because it looks like fat probably in cadavers, so it's not something that we often get to see or have much of a sense of. It disintegrates over time, so it gets smaller and smaller in adult humans. That's probably another reason why we don't get to see it a lot. But that's where our T cells are actually going to school to get, to learn how to be good T cells. And both of these guys have a receptor. The B cell actually has an antibody. And so remember that the antibody looked a little like a, like a this, and that it had like some kind of little specific receptor on the ends of this Y-shaped molecule. Each B lymphocyte has its own special antibody, and these antibodies are actually embedded in the B lymphocyte cell. So this is my B lymphocyte, that's its nucleus. It's not doing a one-eyed thing. The T lymphocyte also has a receptor, but it's actually called a T cell receptor. And it looks more like what you would imagine, like an actual normal receptor, cellular receptor would look like. It's embedded in the cell membrane also. So both my B cells and my T cells pick a very specific receptor molecule that they associate themselves with. That specific molecule is designed or the intention, the value of this molecule is that at some point, it can identify a particular molecule, a pathogen, a particular molecule on a pathogen. And once it has identified that pathogen molecule, then it can initiate like seriously a nuclear war attack that is super effective. Humoral immune response does it one way. The cell mediated response does it another way, but both of them are super powerful, and together super powerful. So you can imagine that if we're going to have these lymphocytes that have so much power, there's actually a pretty rigorous educational process that they have to go through. So let's compare and contrast how B lymphocytes and T lymphocytes get educated to do that thawing.