Final answer:
Rising levels of gonadotropin-releasing hormone (GnRH) trigger the onset of puberty in females. This hormone surge stimulates the production of other hormones, leading to reproductive organ maturation and the commencement of menstruation and secondary sexual characteristics development.
Step-by-step explanation:
The hormone gonadotropin-releasing hormone (GnRH) triggers the onset of puberty, which is the transition that begins female reproductive life. Rising levels of GnRH lead to increased production of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary gland. This hormonal surge then stimulates the ovaries to secrete estrogen, which is central to the development of reproductive organs and the commencement of ovulation and menstruation in females. Additionally, estrogen is responsible for the development of secondary sexual characteristics during puberty, such as breast development and flaring of the hips.