Welcome to episode 6 of the Biology 2402 Lab Series starring the testes. Similar to the ovaries, they are paired sex organs that function as glands. Unlike the ovaries, they're kept outside of the body wall, really.
So they're still technically, you know, in that abdominal pelvic cavity. They're just in an island in a scrotum, this sack of skin and connective tissue held outside the body. Now that's not an optimal place.
mechanically to put delicate organs with lots of pain receptors, if you know what I'm talking about. But it's cooler out there, and evolution chose that option when sperm cells were having trouble being built at a high mammalian body temperature. In any case, in the model on the left, a single testis, T-E-S-T-I-S, is there, surrounded by that circle. This structure is called an epididymis. You don't have to worry about it yet.
The scrotum is this thing right there. Looking at the microscope image, this whole thing, this whole circle thing right here is a seminiferous tubule. And it's like if you took a whole bunch of cooked spaghetti and put it into a bag, it's kind of like that. A bunch of these little tubes going back and forth inside of the testes. These are the physical locations of spermatogenesis, manufacture of sperm.
There are cells in there called nurse cells or Sertoli cells, which you don't have to be able to identify and they're not on your list. But they'd be located in and among these other sperm cells, these things becoming sperm cells. And they're scattered throughout there that they're going to produce that stuff called inhibin, which I'll mention later. Now outside of the seminiferous tubules like here, there, and there are patches of cells called interstitial cells.
Interstitial cells are the ones that are going to be making your testosterone. In the rat itself over here on the right, you can see that this whole big, whoops, son of a gun. Let's see if I can put that back and carry on.
I think I can. Oh, great, great. I love troubleshooting stuff right when I'm working on it. So, son of a gun.
I'm going to go with this because I don't want to do it again. So over here on the rat, you can see, hopefully, this big bag right here is the scrotum. It's been cut, and inside of there is a testis.
This little thing sneaking up here is that epididymis. But again, like I said, you don't have to know that for this section. So let's move on to the hormones. Testosterone, the big one, the famous one, like I said, produced by the interstitial cells. Sometimes you'll see them called latex cells.
And they have a lot of jobs. Now what I say, what I mean by primary male sexual development, I mean testosterone turns the embryo into a phenotypic male. So if you're producing testosterone and you have the receptors for it, as an embryo you develop phenotypically into a male. So you'll develop testes, you'll develop a penis.
Now, male secondary sexual characteristics are also due to the presence of testosterone. So, hairier, larger, greater bone density, you know, non-lactating mammary glands, etc. Testosterone helps make the sperm, it helps sex drive, and it helps maintain bone density. Now, the other guys, actin and inhibin, as you remember from the ovaries presentation, do the same thing. males have an effect of follicle stimulating hormone and Activen stimulates it and Inhibin inhibits it.
Thank you and don't forget to study your photos and other videos.