Question Video: Recalling the Structure That Secretes Progesterone during the Final Part of Pregnancy | Nagwa Question Video: Recalling the Structure That Secretes Progesterone during the Final Part of Pregnancy | Nagwa

Question Video: Recalling the Structure That Secretes Progesterone during the Final Part of Pregnancy Biology • Third Year of Secondary School

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What structure secretes progesterone during the last five months of pregnancy?

02:15

Video Transcript

What structure secretes progesterone during the last five months of pregnancy? (A) Embryo, (B) corpus luteum, (C) graafian follicle, (D) placenta, (E) pituitary gland.

This question is asking us to recall the function of the hormone progesterone in pregnancy and the structure that secretes it.

Let’s start by reviewing what we know about the hormones involved in the maintenance of pregnancy and the structures that produce them. After fertilization, there are several hormones that help support the implanted embryo and the continuation of pregnancy. These hormones include human chorionic gonadotropin or hCG, progesterone, and estrogen.

In the early stages of pregnancy, hCG is produced by the cells that are surrounding a growing embryo that eventually form the placenta. hCG is partly responsible for maintaining the endometrial thickness throughout pregnancy. hCG also ensures that the corpus luteum, a temporary structure in the ovary, continues to secrete progesterone at the beginning of pregnancy.

Progesterone plays an important role during pregnancy by preventing the uterus from contracting and by increasing blood flow to the uterus. After the fourth month of pregnancy, the corpus luteum breaks down. And the placenta takes over the role of secreting progesterone for the remaining months of pregnancy. The placenta also secretes estrogen. During pregnancy, estrogen increases vascularization, or the formation of blood vessels in the uterus, which helps support the developing fetus. So while the corpus luteum secretes progesterone in the first four months of pregnancy, in the later stages of pregnancy, it is the placenta that takes over secreting progesterone.

Now that we have reviewed the hormones involved in the maintenance of pregnancy and the structures that produce them, we are ready to answer the question. The structure that secretes progesterone during the last five months of pregnancy is the placenta.

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