Learner Resource 3
Put these phrases in the correct order to explain the sequence of events occurring during the
menstrual cycle.
a. Oestrogen levels rise. When they reach their peak level, LH is released from the pituitary
gland. This causes ovulation – the secondary oocyte is released from the follicle and travels
down the fallopian tube where, if it meets a sperm, it may be fertilised.
b. FSH travels to the ovary in the blood. It causes a follicle, containing a primary oocyte, to
develop into a dominant follicle containing a secondary oocyte.
c.
If fertilisation does not occur, the corpus luteum breaks down and stops producing
progesterone. The levels of both progesterone and oestrogen in the blood will drop. The
endometrium breaks down and the woman has her period.
d. As the follicle develops, it and the surrounding tissue within the ovary produce oestrogen.
e.
If the ovum is fertilised, it will implant into the endometrium and produce HCG, which causes
the corpus luteum within the ovary to continue to produce progesterone. This ensures the
endometrium remains in place and the pregnancy continues.
f.
Woman starts her period. Levels of oestrogen and progesterone are low. Negative feedback
from these hormones no longer affects the pituitary gland.
g. Progesterone causes the endometrium to thicken further and become more vascular.
h. Oestrogen causes the endometrium lining the uterus to thicken. It also has a negative
feedback effect on the pituitary preventing the production of FSH.
i.
FSH is released from the pituitary gland.
j.
After the secondary oocyte has been released, what remains of the follicle, now known as the
Graffian follicle, starts to produce progesterone. This has a negative feedback effect on the
pituitary preventing the release of further FSH or LH.
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Fertility and assisted reproduction delivery guide
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© OCR 2016