[NOISE] [MUSIC] So the immune system is remarkable in that it protects every body tissue and every body surface. We tend to think of the immune system as being confined to the blood system in some way, because that's where we often take samples to measure white blood cells and immune responses, but actually it's function in each body system is very, very different. So in the respiratory system we understand how it has a large surface area to cover, and it's the immune defenses of the upper respiratory tract of the nose, and the upper airways, and the trachea, and the larynx are different than the lower respiratory tract, the lungs and the alveoli. So the immune system is different within a body system, even at different locations. That's true too for the intestinal tract. So the intestinal tract is the body surface in which every individual is exposed to the most microbes. It's a massive number of microbes that inhabits the intestinal tract and every single day they're changing. There are new proteins entering into the intestinal tract and the immune system has to differentiate between pathogenic proteins, pathogenic bacteria, and friendly commensurable bacteria and non-threatening proteins. But the immune system has to also protect other body systems such as the reproductive immune system, the reproductive system as well, and that's different between the male and the female. And reproductive infections and reproductive disease is an important part of the efficiency and inefficiency of our livestock production systems. As we know, the efficiency of breeding is part of the cycle of most of our species. We have to have, in the dairy system, we have to have a new calf every year for the cow to be able to be lactating and to produce milk. For the beef system, the production of a calf every year, and that calf being raised for meat, that's an important part. So if you produce less than one calf a year, you have an inefficient system. For piglets, the pig system, the number of piglets and the ability of sows to reproduce no regular intervals, that's an important part of the efficiency of that system. For sheep and for goats as well, they're seasonal breeders. They only get a chance to breed, sheep only get a chance to breed once a year, so making sure that you get the most offspring from that single breeding cycle is important. Otherwise you've fed the dam and fed the rams the whole period of time and they don't produce. So reproductive efficiency is really important, and preventing and management of reproductive diseases is an important part of our system. But the immune system works differently at the reproductive surfaces. The reproductive surfaces of the female, the vaginal tract and the reproductive tract all the way going into the uterus, that's a remarkable environment because that is the home of the fetus. So the dam accepts sperm from the male, that's a foreign protein and the immune system doesn't reject it. The sperm then meets the egg in the reproductive tract, and then the sperm invades the egg and that egg doesn't reject that sperm. It does sometimes, but for conception to occur, there has to be a normal process. So that seems like a foreign invader, and yet the immune system doesn't repel that infection. You see during the reproductive cycle the hormones, the endocrinology of the reproductive cycle occurs in such a way that it actually down-regulates and up-regulates immune responses at certain parts of the reproductive tract, at specific stages of that cycle. So it allows the sperm to meet the ovum and for that conception to occur. It allows this conceptus, which again is about 50% foreign genetic material, to attach inside the uterine lining. You'd think if that was a foreign substance that the uterus would produce an immune response which would reject that fetus. But the immune system in the lining of the uterus is controlled, both systemically and locally, by hormones and cellular movements such that the conceptus can become established. And an individual that is 50% genetically different has all of these foreign proteins, does not get rejected in the normal pregnancy. So the immune system of the female reproductive tract is remarkable. It allows, at certain stages of the reproductive cycle, under hormonal control, it allows these processes to take place. Similarly with the male reproductive tract. The male reproductive tract is metabolically very active. The male bull or the male ram or the male boar produces a huge amount of sperm every day. But these sperm take about 60 to 90 days to develop, and they move along the reproductive tract. So this here is a picture of the male reproductive tract. The sperm being produced in the testes and then moving along through the epididymis, into the vas deferens. So, the sperm that are produced inside the testes are stored in this area for about two months. So you have these living cells, these cells that need to be healthy, but some of which will die and need to be removed. And then during the reproductive process, the sperm is then exposed to different secretions along the reproductive canal and then through this structure which is unique shape for the ruminant. This is a sigmoid flecture penis, and then into the ejaculate, and into the female. But immune system of this part of the reproductive tract is very, very specific. You can't have too many immune reactions taking place in the testis. If you had inflammation in the testis, the temperature of the testicle would change and the testis live outside the body because the sperm need a lower temperature to survive and to develop. So if you have any inflammation and an increase in heat, then you can damage the production of sperm. So the immune system of the testes is designed to protect it against advanced immune reactions, which would kill those sperm. So again, the reproductive system of this part of the body is specifically designed to protect it's function. And when you get an infection, it doesn't take too much of an infection to impede reproduction. If we have an infection in the testes or in the epididymis, or along one of the reproductive organs such as the seminal vesicles, or the ampulla, or the prostate, any of those infections would produce immune cells which would kill the sperm. So infections within the reproductive tract can affect the viability of those sperm that are being placed inside of the female and therefore stop conception taking place. Similarly, infections in the reproductive tracts of females, if you have an infection of the lining of the uterus, that could be severe because it could prevent pregnancy and prevent conception. An infection in the ovary or in the lining of the tract, the ovary duct, that conduct eggs. Any affection in those sites can be very damaging to the fragile metabolism of the ovum. Just as an affection of the reproduction tract of the male is damaging to the metabolically fragile sperm. So, monitoring your animals for reproductive infections is very, very important. And taking care of the reproductive immunology, again, is very, very important in preventing these infections. [MUSIC]
