Locate progesterone production after ovulation
Post-ovulation source: remaining follicle → corpus luteum in ovary → progesterone in blood → maintained uterine lining. Source breakdown and lining shedding occur in different organs.
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
Where is the main cycle source of progesterone after ovulation?
What you will learn
- Explain the corpus luteum as an endocrine source
- Connect source persistence with lining support
Original teaching model.
| Feature | Meaning |
|---|---|
| Origin | Remaining ovarian follicular tissue |
| Source | Corpus luteum |
| Signal and target | Progesterone → uterine lining |
| No established pregnancy | Source breaks down; support falls |
Explain the corpus luteum as an endocrine source
Progesterone is produced mainly by the corpus luteum in the ovary after ovulation during the menstrual cycle. The corpus luteum develops from the remaining follicular tissue after egg release. It is a temporary endocrine structure, not the released egg and not the uterine lining. This source relationship explains why the progesterone rise follows ovulation in a typical cycle.
Progesterone travels in the blood and helps maintain the prepared uterine lining. The hormone source lies in an ovary, whereas the lining lies in the uterus. A source question and a target question therefore have different answers. The corpus luteum also produces oestrogen, so calling it a progesterone-only container oversimplifies its endocrine function.
Connect source persistence with lining support
If pregnancy is not established, the corpus luteum later breaks down and its hormone production declines. Reduced progesterone and oestrogen support contributes to shedding of the lining at the next menstruation. Breaking down the corpus luteum is an ovarian change; shedding the lining is a uterine change. Do not exchange the locations when explaining the linked sequence.
The original post-ovulation source map shows a remaining follicle, corpus luteum and blood-borne progesterone. Arrows represent sequence and secretion, not an egg transforming into a placenta. Early pregnancy can prolong corpus-luteum function, while later pregnancy has a major placental source. The changing pregnancy sources are considered in the next lesson.
Pause and explain
What happens if corpus-luteum hormone support declines in a non-pregnant cycle?
Worked example
Why can the corpus luteum support lining in another organ?
Show the worked solution
- Identify secretion of progesterone into blood.
- Identify uterine lining as the responding target.
Answer The ovarian corpus luteum secretes progesterone into blood, which carries the signal to the uterine lining and supports its maintenance.
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.
Trace the source origin, hormone and target after ovulation.
Give me a hint
Start with remaining follicular tissue.
Compare my reasoning
- Name corpus luteum and progesterone.
- Name blood transport to uterine lining.
Remaining follicle → ovarian corpus luteum → progesterone in blood → maintenance of uterine lining.
Look for these in your work
- Give the source origin
- Connect signal and target
Explain the linked ovarian and uterine events when pregnancy is not established.
Give me a hint
Separate source breakdown from target shedding.
Compare my reasoning
- Describe corpus-luteum breakdown and hormone decline.
- Describe subsequent loss of lining support and shedding.
The corpus luteum breaks down in the ovary; progesterone and oestrogen fall, and the uterine lining later sheds at menstruation.
Look for these in your work
- Name both organs
- Include the connecting hormone decline
Correct “the egg becomes the lining, which secretes the ovarian progesterone”.
Give me a hint
Repair origin, source and target separately.
Compare my reasoning
- Place corpus luteum origin in remaining follicle.
- Place progesterone source in ovary and target in uterus.
The remaining follicle becomes the corpus luteum in the ovary; it secretes progesterone, which supports the uterine lining. The released egg is separate.
Look for these in your work
- Correct all three roles
- Do not turn a gamete into lining
Common mistakes
- Corpus luteum and lining occupy different organs.
- The released egg does not become the corpus luteum.
What can you explain now?
What happens if corpus-luteum hormone support declines in a non-pregnant cycle?
Compare with the explanation
The lining later sheds as menstruation
Progesterone and oestrogen support fall.
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Make it stick
Explain explain the corpus luteum as an endocrine source and connect source persistence with lining support. 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.