Final answer:
The hormone crucial for ovulation and the maturation of ovarian follicles is luteinizing hormone (LH), which, along with FSH, is released by the pituitary gland in response to GnRH and triggers the release of the egg and the formation of the corpus luteum.
Step-by-step explanation:
The hormone crucial for ovulation and the complete maturation of a client's ovarian follicles is luteinizing hormone (LH). Although follicle-stimulating hormone (FSH) is also integral in the maturation process of follicles, it is the surge of LH that triggers ovulation and the eventual transformation of the remaining follicular cells into the corpus luteum.
During the menstrual cycle, FSH and LH work in tandem, with FSH priming the follicles and LH completing their maturation. The pituitary gland releases these hormones in response to gonadotropin-releasing hormone (GnRH) from the hypothalamus. The increase in estrogen from the growing follicles peaks just before ovulation, which leads to a surge in LH release. This LH surge is the catalyst for the release of the egg from the mature follicle. Post-ovulation, LH assists in the luteinization of the granulosa and theca cells, allowing the corpus luteum to secrete progesterone for potential pregnancy maintenance.