Which hormones are primarily active during the follicular phase?

The correct answer identifies that Follicle Stimulating Hormone (FSH) and Estrogen are primarily active during the follicular phase of the menstrual cycle.

During the follicular phase, which begins on the first day of menstruation and lasts until ovulation, FSH is secreted by the pituitary gland and plays a critical role in stimulating the growth and maturation of ovarian follicles. These follicles, in turn, produce Estrogen, a key hormone involved in the regulation of the menstrual cycle and the development of female secondary sexual characteristics.

Estrogen levels rise as the follicles develop, leading to the thickening of the uterine lining in preparation for a potential pregnancy. This surge in estrogen also provides feedback to the hypothalamus and pituitary gland to modulate the production of hormones, leading to the eventual LH surge that triggers ovulation.

In summary, the focus on FSH and Estrogen during the follicular phase is vital for follicular development and preparation for ovulation, making this pairing the most relevant hormones in this phase of the menstrual cycle.