Final answer:
The relative age of a female based on follicular development stages pertains to the menstrual cycle's follicular phase where ovarian follicles mature due to FSH and LH, leading to ovulation approximately every 28 days, followed by the luteal phase and eventually, menstruation.
Step-by-step explanation:
The relative age of a female based on follicular development stages is a concept rooted in the biology of the menstrual cycle. The follicular phase is the first half of the ovarian cycle and is characterized by the growth of ovarian follicles, stimulated by rising levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
Estrogen is also produced by the growing follicles, which plays a crucial role in preparing the endometrium for potential pregnancy.
During the follicular phase, follicles progress from primordial, to primary, to secondary, and finally to tertiary stages, ending in the ovulation of a secondary oocyte. This is typically a 28-day cycle in humans, though the length can vary. The maturating follicle that leads to ovulation is known as the Graafian follicle.
After ovulation, the luteal phase begins, marked by the transformation of the ruptured follicle into the corpus luteum, which produces progesterone to prepare the uterus for a fertilized egg. If no fertilization occurs, this cycle concludes with menstruation, and the menstrual and ovarian cycles restart.
Recalling that a female infant is born with one to two million oocytes, the number of these declines throughout life until menopause. The process of follicles dying off without reaching maturity is known as atresia and can occur at any stage during the follicular development.