A Western blot analysis of the expression of estrogen receptors in ovarian tissues at different times of the estrous cycle showed approximately four times greater protein levels at day 2 compared with day 10 of the cycle.Which of the following may be true given these data?
A) Estrogen is acting as an endocrine signal in the ovaries.
B) Estrogen is acting as an autocrine signal in the ovaries.
C) Ovaries only secrete estrogen early in the estrous cycle.
D) Ovarian tissue is responsive to estrogen only early in the estrous cycle.

Question

Quizplus · Accepted Answer

The increased levels of estrogen receptors in ovarian tissues at day 2 compared with day 10 of the cycle suggest that estrogen is likely acting as an autocrine signal in the ovaries during the early stages of the estrous cycle. Autocrine signals act on the same cells that produce them, and in this case, the ovarian tissues are likely producing estrogen and responding to it via the increased expression of estrogen receptors. The data do not suggest that estrogen is only acting as an endocrine signal, as it may also be acting locally in the ovaries through autocrine signaling. Additionally, the data do not suggest that estrogen is only produced early in the estrous cycle or that ovarian tissue is only responsive to estrogen early in the cycle.

A Western Blot Analysis of the Expression of Estrogen Receptors