Stage 1 – Menstruation Starts on Day 1 – lasts 3-7 days Hormones – travel in blood to target tissue – ALL 4 hormones at lowest levels Ovary – – Follicle – just starting to grow – cycle is starting over Uterine lining (endometrium) – is being broken downs and shed from previous cycle

Stage 2 – Follicle Stage Also starts on Day 1 – lasts up to 14 days overlaps Stage 1 Hormones – travel in blood to target tissue – Pituitary – FSH ↑– stimulates follicle to grow and develop – Ovary – Estrogen ↑– causes endometrium to grow Ovary – – Follicle – grows AND produces estrogen Uterine lining (endometrium) – grows and thickens following menstruation due to increasing estrogen levels

Menstrual Cycle - Ovary

Stage 3 – Ovulation Usually on Day 14 (or mid-cycle) – 1 day Hormones – travel in blood to target tissue – Pituitary – LH spikes – Ovary – Estrogen at highest level Ovary – – Follicle ruptures and releases egg into oviduct Uterine lining (endometrium) – continues to grow and thicken

Menstrual Cycle – Pituitary Hormones

Stage 4 – Luteal Days – lasts about 14 days Hormones – travel in blood to target tissue – Pituitary – LH ↑– causes corpus luteum to develop from remaining portion of the follicle – Ovary – Progesterone ↑– causes endometrium to grow Ovary – – Corpus Luteum develops and then breaks down as LH levels fall off Uterine lining (endometrium) – continues to grow and thicken due to progesterone levels

Menstrual Cycle – Uterine Lining

Menstrual Cycle - regulation