# A reproductive twofer: production of uterine lining and sperm

**URL:** <https://boards.straightdope.com/t/a-reproductive-twofer-production-of-uterine-lining-and-sperm/300637>\
**Category:** Factual Questions\
**Created:** [April 22, 2005, 5:32pm UTC](https://boards.straightdope.com/t/a-reproductive-twofer-production-of-uterine-lining-and-sperm/300637 "2005-04-22T17:32:17Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![pasunejen](https://avatars.discourse-cdn.com/v4/letter/p/58956e/32.png) [@pasunejen](https://boards.straightdope.com/u/pasunejen)\
**Post date:** [April 22, 2005, 5:32pm UTC](https://boards.straightdope.com/t/a-reproductive-twofer-production-of-uterine-lining-and-sperm/300637/1 "2005-04-22T17:32:17Z")

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I’ve been sitting around pondering various ponderments, and it occurred to me that while I know the basics of 1) the menstrual cycle and 2) semen production, I do _not_ know:

1. By what process does the uterine lining thicken? Where does the blood come from?

2. How are sperm actually produced in the testes?

These may actually be dumb questions, but I’m curious.

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**Author:** ![Sevo](https://avatars.discourse-cdn.com/v4/letter/s/ed655f/32.png) [@Sevo](https://boards.straightdope.com/u/Sevo)\
**Post date:** [April 22, 2005, 7:20pm UTC](https://boards.straightdope.com/t/a-reproductive-twofer-production-of-uterine-lining-and-sperm/300637/2 "2005-04-22T19:20:21Z")

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I’m so frustrated. I answered this with nice detailed explanations and then the hampsters ate my reply. Argh.

Here were the two links I had given (these pictures might help):

[Menstrual Cycle](http://bio.classes.ucsc.edu/bio80as/FiguresandIllustrations/FemReproCycle.gif) The cellular lining grows, the blood vessels grow in it, and then when everything regresses/sloughs there’s bleeding until the vessels clot up. All of this is controlled by the hormones in the picture.

[Sperm Production](http://www.creationofman.net/chapter1/rescreation/yaratilis183.jpg) Nice picture of sperm production. The details are more complicated but that picture is probably what you’re looking for.

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**Author:** ![pasunejen](https://avatars.discourse-cdn.com/v4/letter/p/58956e/32.png) [@pasunejen](https://boards.straightdope.com/u/pasunejen)\
**Post date:** [April 22, 2005, 8:45pm UTC](https://boards.straightdope.com/t/a-reproductive-twofer-production-of-uterine-lining-and-sperm/300637/3 "2005-04-22T20:45:46Z")

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Thank you!