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Ovulation is the process by which a mature egg (ovum) is released from the ovary into the fallopian tube, typically occurring approximately midway through the menstrual cycle in human females (around day 14 of a 28-day cycle). This release is triggered by a surge in luteinizing hormone (LH) secreted by the pituitary gland, which causes the mature follicle housing the egg to rupture and expel the ovum. The released egg is swept into the fallopian tube by finger-like projections called fimbriae and remains viable for fertilization for approximately 12-24 hours. Ovulation represents the fertile window in the reproductive cycle when conception is possible, and it is influenced by hormonal regulation involving complex feedback loops between the brain, pituitary gland, and ovaries.

Implantation is the process by which a developing embryo (at the blastocyst stage) attaches to and embeds itself within the endometrium (uterine lining), typically occurring 6-10 days after fertilization. Following fertilization in the fallopian tube, the zygote undergoes several cell divisions while traveling toward the uterus, transforming into a hollow ball of cells called a blastocyst. Upon reaching the uterus, the blastocyst hatches from its protective zona pellucida coating and adheres to the thickened, hormone-prepared endometrial surface. The outer cells of the blastocyst (trophoblast) then invade the uterine tissue, establishing the intimate connection that will develop into the placenta. Successful implantation is essential for pregnancy to continue, as it establishes the maternal-fetal interface necessary for nutrient and gas exchange, hormonal support, and waste removal throughout gestation. Implantation triggers the release of human chorionic gonadotropin (hCG), the hormone detected by pregnancy tests, which maintains the corpus luteum and its progesterone production essential for sustaining early pregnancy.