Ovarian Cycle
luteal phase:
- once the follicle has ruptured and expelled its egg into Fallopian tube (oviduct), the remaining follicle may be transformed into the corpus luteum
- corpus luteum secretes progesterone which is important for: 1) implantation of the egg into the uterine wall, and 2) maintenance of pregnancy
- in some species, corpus luteum is “spontaneously functional”, in other species, vaginal-cervical stimulation during copulation is required for formation of corpus luteum
- length varies depending on species; in humans, lasts 10-12 days
menstrual phase: (species dependent)
- see uterine bleeding in species that have long ovarian cycles (primates)
- during luteal phase, estrogen and progesterone prepare uterus for implantation
- if the egg is not fertilized, then no embryo will implant into uterine wall, the corpus luteum will regress (die)
- drop in estrogen and progesterone levels will lead to sloughing off of the uterine wall (endometrium)--”uterine bleeding”
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