Locate oestrogen production through the ovarian cycle
Oestrogen sources in the cycle: developing ovarian follicles and, after ovulation, the corpus luteum. The uterine lining is a target for rebuilding, not the ovarian source.
Exam scope and assessment notes
Extended only (Supplement) · Biology 0970, 2026–2028. Use the stated specimen features and evidence. Diagrams are schematic. Written practice is self-checked; human subject-teacher review, supervised practical competence and cumulative assessment remain pending. Cambridge states that IGCSE 0970 has the same subject content as IGCSE 0610, with 9–1 grading. This StudyForA pathway maps the 2026–2028 syllabus only. This 9–1 graded qualification is available only in a limited number of administrative zones. Confirm that your centre can enter you for this code and exam series with Cambridge International. Cambridge has published a separate syllabus for 2029. StudyForA has not reconciled that version yet; this page supports exams in 2026, 2027 and 2028 only.
Before you begin
- Recall endocrine glands, blood-borne hormones, ovaries, testes, uterine lining, ovulation and implantation.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which is an oestrogen source before ovulation?
What you will learn
- Name ovarian structures producing oestrogen
- Separate a hormone source from its target
Original teaching model.
| Feature | Meaning |
|---|---|
| Before ovulation | Developing ovarian follicle |
| After ovulation | Corpus luteum also secretes oestrogen |
| Transport | Blood |
| Target response | Uterine-lining rebuilding |
Name ovarian structures producing oestrogen
During the menstrual cycle, oestrogen is produced in the ovaries. A developing follicle is an important source before ovulation. Follicular cells secrete hormone into blood as the follicle develops. The egg enclosed by the follicle is not itself a bottle of hormone sent down an oviduct: distinguish the endocrine tissue from the gamete it surrounds.
After ovulation the remaining follicular tissue forms the corpus luteum, which produces progesterone and also oestrogen. It would therefore be misleading to claim that oestrogen production can only occur before egg release. A typical cycle includes a rise before ovulation and a smaller rise later; the precise values in any classroom graph are model values rather than a reference range.
Separate a hormone source from its target
The uterine lining is a responding target for oestrogen, not the ovarian source in this explanation. Oestrogen supports rebuilding and thickening of the lining. Blood transport connects a source in the ovary with a target in the uterus. A complete source question requires an organ or tissue; a complete function question requires the response as well.
The original source map contrasts developing follicle and corpus luteum, then connects both to blood-borne secretion. Pregnancy introduces an additional placental source later, which is treated separately. Do not assume that the tissue receiving hormone must be the tissue that secreted it, or that a graph showing a rise directly photographs the source.
Pause and explain
Which source can also produce oestrogen after ovulation?
Worked example
Name an oestrogen source before and after ovulation.
Show the worked solution
- Identify developing ovarian follicle before release.
- Identify corpus luteum after release.
Answer Developing ovarian follicles produce oestrogen before ovulation; the ovarian corpus luteum also produces oestrogen after ovulation.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
State the organ and structure producing much of the pre-ovulation oestrogen.
Give me a hint
Give a broad organ and a more precise tissue.
Compare my reasoning
- Name ovary.
- Name developing follicle.
The ovary, especially the developing follicle, produces oestrogen before ovulation.
Look for these in your work
- Name organ
- Name follicle
Explain why “only the egg secretes all oestrogen” is an inaccurate source statement.
Give me a hint
Separate enclosed gamete from endocrine tissues.
Compare my reasoning
- Name developing follicular tissue.
- Include corpus luteum after ovulation.
Oestrogen is secreted by ovarian tissues including developing follicles and later the corpus luteum; the egg is not the sole endocrine source.
Look for these in your work
- Correct the tissue category
- Include both stages
A diagram labels uterine lining as source and follicle as target. Repair the pre-ovulation pathway.
Give me a hint
Trace secretion, blood transport and response.
Compare my reasoning
- Place secretion in ovarian follicle.
- Place rebuilding response at uterine lining.
Ovarian follicle → oestrogen in blood → uterine-lining rebuilding and thickening.
Look for these in your work
- Correct direction
- Separate source and response
Common mistakes
- A target is not necessarily a source.
- Oestrogen production does not stop simply because ovulation occurred.
What can you explain now?
Which source can also produce oestrogen after ovulation?
Compare with the explanation
Corpus luteum in the ovary
It also secretes progesterone.
After trying it yourself, choose your next review. This is your self-assessment.
Your review choice appears on Today. Sign in to sync it across devices.
Make it stick
Explain name ovarian structures producing oestrogen and separate a hormone source from its target. Follow the event arrows or graph labels before opening the solutions.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.