Answer to Question 1
Answer: The rodent estrous cycle is four days in length and involves the secretion of estradiol followed by progesterone. Exposure of a female mouse to the odor of other female mice can slow their estrous cycles (Lee-Boot effect), while exposure to a male mouse can restart the cycle (Whitten effect). Moreover, the urine from a male mouse can speed up the onset of puberty (Vandenbergh effect) or can cause a pregnant female to abort a fetus fathered by another male mouse (Bruce effect). These effects require an intact vomeronasal system.
Answer to Question 2
Answer: The anterior pituitary starts the cycle by the secretion of FSH, which acts on the ovarian follicles to secrete estradiol into the bloodstream. Increasing estradiol levels act on the anterior pituitary to produce a surge of luteinizing hormone (LH), which causes a follicle to rupture, thereby releasing the ovum. The ruptured follicle (corpus luteum) secretes estradiol and progesterone, which prepare the uterine lining for implantation of the ovum (if fertilized). If no implantation occurs, then estradiol/progesterone secretion stops, and the uterine lining is shed, thus resulting in blood flow (menstruation).
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