When cows have twin calves of unlike sex (fraternal twins), the female twin is usually sterile and has masculinized reproductive organs. This calf is referred to as a freemartin. In cows, twins may share a common placenta and thus fetal circulation. Predict why a freemartin develops.

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Hi everyone, welcome back. Let's look at our next problem. It says which of the following statements is true about free martin is um let's look at our following statements. We have four different statements and then our answer choices. A through d are different selections of those statements. We want to look at which ones are correct. Number one says a sterile female cow born along with a twin male cow. Well, this is correct. Re martin is um occurs when you have a sterile female uh with that's somewhat masculine. Ized um born with a male twin and it occurs because of extensive vascular connections between the placentas of the twins that cause shared blood circulation. As a result, the female is exposed to the anti malaria and hormone, which is one of the male hormones and therefore develops masculine characteristics and is born sterile with nonfunctioning ovaries. Um The calf is fanatically female but has um issues with its reproductive development. So let's look at statement to here caused by the circulation of anti malaria and hormone M. I. S. In utero. And this is correct. And yes, the two ins share a circulation and so the female twin gets exposed to this masculine. Izing hormone Statement three says Free Martin. Ism can occur in humans. This is incorrect. It occurs rarely in some other mammals but not in humans which do not share the circulation when you have male and female twins. The way male and female twin calves do steven. Four says inspection of the female genitalia in newborn calves reveals no anomalies. This is also incorrect. Um Often there are some subtle anomalies in the female genitalia upon inspection of the newborn calf. So when we look down at our answer choices, we're looking for the one that has one and two being correct and we see that's choice c. one and two. Choice A is one only, but of course Choice two is correct as well. Choice B. Is two and three, but three is incorrect and Choice D. Is 12 and four but four is incorrect. So that's not our answer choice. So again, which of the following statements is true about free Martin is um choice c. one and to see you in the next video.

When cows have twin calves of unlike sex (fraternal twins), the female twin is usually sterile and has masculinized reproductive organs. This calf is referred to as a freemartin. In cows, twins may share a common placenta and thus fetal circulation. Predict why a freemartin develops.

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Key Concepts

Freemartinism and Sexual Differentiation

Placental Blood Sharing in Twins

Role of Androgens in Reproductive Organ Development