Explain the LH surge ovulation and corpus luteum formation
Pituitary LH surge → ovulation → corpus-luteum formation/function. Corpus luteum then produces ovarian progesterone and oestrogen; ovulation is not fertilisation.
Section 16.5 · Sex hormones in humans
Extended only (Supplement); Biology 0610, 2026–2028. Use the stated specimen features and evidence. Diagrams are schematic. Written practice is self-checked
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 hormone surge triggers ovulation?
What you will learn
- Trace pituitary LH to ovarian release
- Connect remaining follicular tissue with progesterone production
Original teaching model.
| Feature | Meaning |
|---|---|
| Source | Pituitary gland |
| Surge effect | Triggers ovulation |
| Later ovarian effect | Corpus-luteum formation and function |
| Separate process | Gamete nuclear fusion is fertilisation |
Trace pituitary LH to ovarian release
Luteinising hormone, abbreviated LH, is secreted by the pituitary gland and reaches ovarian tissues in the blood. A marked rise, called the LH surge, triggers ovulation. The released egg is distinct from the follicular tissue remaining in the ovary. LH does not fuse gamete nuclei and does not by itself establish fertilisation or pregnancy.
LH also promotes formation and function of the corpus luteum from the remaining follicular tissue. The corpus luteum produces progesterone and oestrogen. This links pituitary secretion with the post-ovulation ovarian hormone source and the maintained uterine lining. The source of LH is not the same as the source of progesterone.
Connect remaining follicular tissue with progesterone production
The original event chain places LH surge before egg release, then corpus-luteum formation and progesterone support. A typical hormone curve can help identify the ordering, but a graph drawn from invented levels cannot diagnose real ovulation. In a teaching model where release is explicitly stipulated, use that event rather than claiming that an isolated peak proves nuclear fusion.
A good comparison distinguishes FSH promoting follicle development from LH triggering ovulation and supporting the corpus luteum. They are both pituitary hormones, but that shared source does not make their principal named roles identical. Keep event, hormone and tissue labels separate when explaining the complete cycle.
Pause and explain
What is the corpus luteum relationship here?
Worked example
Name the signal triggering ovulation and the tissue formed afterward.
Show the worked solution
- Name pituitary LH surge.
- Name corpus luteum from remaining follicle.
Answer The pituitary LH surge triggers ovulation; remaining follicular tissue forms the corpus luteum, supported by LH.
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.
Write the LH source and the two named ovarian effects.
Give me a hint
Separate release and post-release tissue support.
Compare my reasoning
- Name pituitary and ovulation trigger.
- Name corpus-luteum formation/function.
Pituitary LH triggers ovulation through its surge and promotes formation/function of the corpus luteum.
Look for these in your work
- Include source
- Give both effects
Compare the main cycle roles of FSH and LH.
Give me a hint
Both sources match but their effects differ.
Compare my reasoning
- Give FSH follicle development and oestrogen stimulation.
- Give LH surge ovulation and corpus-luteum support.
Both come from pituitary: FSH stimulates follicle development and oestrogen production; LH surge triggers ovulation and LH supports corpus luteum.
Look for these in your work
- Use matched categories
- Distinguish the effects
A model has an LH surge followed by egg release, without sperm observations. Does it prove fertilisation?
Give me a hint
Distinguish release from nuclear fusion.
Compare my reasoning
- Recognise the stipulated ovulation event.
- Require evidence of sperm–egg nuclear fusion for fertilisation.
It supports the stated ovulation sequence; it does not prove fertilisation because sperm–egg nuclear fusion is not shown.
Look for these in your work
- Retain the supported release event
- Reject unsupported fusion
Common mistakes
- An LH surge does not fuse nuclei.
- LH and progesterone have different sources.
What can you explain now?
What is the corpus luteum relationship here?
Compare with the explanation
LH supports remaining follicular tissue forming an endocrine structure
It produces progesterone and oestrogen.
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Make it stick
Explain trace pituitary lh to ovarian release and connect remaining follicular tissue with progesterone production. 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.