Reproductive Body Parts

Ovaries, fallopians, the womb, cervix, fornix and vagina. Also those random random menstrual cycles.

This explains about reproductive body parts and what happens during the menstrual cycle. I’ve also got a resource about fertility (how periods and menstrual cycles work) you might find useful.

Ovaries

Where eggs are stored and released. 1 or 2 eggs are released in each menstrual cycle (this is ovulation). If you have ovaries then all the eggs that are released over your life time are there when you are born. At the beginning of puberty, eggs start to be released from the ovaries (and that’s what starts off the first period).

Read more about how puberty works here

Womb

Fertilised eggs attach here and grow during pregnancy. Before eggs are released a sticky lining is created so that a fertilised egg (embryo) can stick to the womb, starting pregnancy. It’s also known as the uterus.

Fallopian tubes

The fallopian tubes connect the womb towards the ovaries. As you can see in the pictures here the tubes don’t actually attach to the ovaries. The fallopian tubes are where sperm meet eggs during fertilisation.

Vagina and fornix

The vagina is very stretchy and widens and lengthens when sexually aroused and also through pregnancy and giving birth. It’s surrounded by lots of muscle so after stretching it goes back to normal size. The fornix are deep inside the vagina surrounding the cervix. During birth they stretch massively. This part of the vagina also stretches lots during sex, so long as the vagina is aroused.

Read more about the vagina and clitoris.

Cervix

This is the neck of the womb. There is a very small gap here allowing sperm to swim into the womb. During pregnancy the cervix part to allow the baby through. It’s also where smear tests are taken to look for cervical cancer. You can find out more about this at the NHS website about cervical screening.

Menstrual cycle

An egg (or two) is released from the ovary once in a menstrual cycle: this is known as ovulation and happens around halfway through the cycle (it is not at the same time as a period).The egg dies around 24 hours after being released. After that it is not possible to get pregnant until the next egg is released in the next cycle. Unfertilised eggs, womb lining and a little bit of blood then come out, a few days later, during a period. The first day of a period is the first day of a new cycle, as this graphic shows.

Although there are times of the cycle when people can’t get pregnant, it is very very difficult to work out when this is. Cycle length can change from cycle to cycle totally randomly. Because you don’t know the length of your current cycle until the beginning of the next one, it’s not possible to know for sure when the ‘safe’ period was. Make sense?

Many people use tracker apps to help them to track their cycle, however they aren’t as accurate as you might think. I’ve got advice here about how to track your own menstrual cycle, including a nice year calendar.

Further reading

You might also be interested in balls / testicles and ejaculation and how the penis works and maybe also the clitoris and vagina too.

© Justin Hancock, 2026 Find out more about me and BISH here. If you’re an educator, head to my website BISH training, to find out about my resources for SRE and training for practitioners.

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BISH is run by me, Justin Hancock. I’ve been a trained sex and relationships educator since 1999. I’m a member of the World Association for Sexual Health. As well as BISH I also have resources, a podcast, and a coaching service for over 18s, as well as some of the best RSE teaching resources around. Find out out about my other work at justinhancock.co.uk. My work has featured (positively) in the media, like the BBC, Financial Times, The Economist, The Guardian, Sky One, and Novara Media.

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