Sexual Anatomy and Puberty: A Teen’s Guide
Understanding the External Genitals
Every person’s body is unique, but the external genitals fall into two basic types. In males, the external genitalia include the penis and scrotum (a skin pouch holding the testes). The penis contains the urethra (a tube for urine and semen) and special spongy tissue that fills with blood to cause erections. The scrotum holds the two testes, which produce sperm and the hormone testosterone. At puberty (around age 11–12 for most boys), the penis and testes grow larger and pubic hair appears.
In females, the external genital area is called the vulva, which includes several parts. The labia majora (“large lips”) and labia minora (“small lips”) are skin folds that protect the inner genitals. These labia come in different sizes and shapes for everyone. At puberty (often starting around age 10–11 for girls), the labia grow, and hair grows on the labia majora. The clitoris is a small, highly sensitive organ at the top of the vulva. Below it are the vaginal opening (where menstrual blood and babies exit) and the urethral opening (where urine exits). All of these parts allow menstruation, urination, and pleasure. As girls hit puberty, the clitoris and labia become more pronounced and may be stimulated during sexual arousal (see next section).
Internal Reproductive Structures
The internal sex organs work with the external genitals. In males, the testes in the scrotum make sperm, which travel through a tube called the vas deferens. During ejaculation, sperm mix with fluids from the seminal vesicles and prostate gland to form semen. This semen then exits the body through the urethra in the penis during orgasm. The male internal system also includes the cowper’s glands, which produce a clear fluid (pre-ejaculate) to lubricate the urethra. All these organs help males make sperm, discharge it, and also urinate (pee).
In females, the internal organs are housed inside the pelvis. The vagina is a flexible canal that connects the external opening to the uterus. The cervix is the lower part of the uterus that opens into the vagina. The uterus (or womb) is a hollow, pear-shaped organ where a fertilized egg can implant and a baby can grow. On either side of the uterus are two ovaries, which make eggs (ova) and female hormones. When an ovary releases an egg, it travels through one of the fallopian tubes (thin tubes attached to the uterus) toward the uterus. If sperm meets the egg in the tube, fertilization can occur; the fertilized egg then implants in the uterine lining (leading to pregnancy). These organs also work together to cause menstruation: each month, hormone changes prepare the uterus for pregnancy, and if no pregnancy happens, the uterine lining is shed as a period. Understanding these internal parts helps explain how bodies change and reproduce.
How Genitals Function During Sexual Arousal
During sexual arousal, both male and female genitals undergo physical changes. In a male, arousal causes the penis to become erect (hard) because blood rushes into its spongy chambers. At the same time, males may feel more sensitive and eventually ejaculate semen through the penis. In females, the clitoris (often called the “pleasure center” of the vulva) swells with blood and becomes more sensitive. The labia (both majora and minora) also fill with blood and may expand slightly, and the vagina itself lubricates (produces moisture). This natural lubrication comes from the vaginal walls and from glands such as the Bartholin’s glands, making sexual activity more comfortable. In males, the Cowper’s glands produce pre-ejaculate fluid during arousal, which helps neutralize acidity in the urethra. These processes prepare both bodies for sexual activity. Nerve endings in these areas create pleasurable sensations. For example, the clitoris alone contains over 10,000 nerve endings. With continued stimulation, both males and females can reach orgasm, which is when intense pleasure and muscular release occur.
Anatomy Myths and What’s Normal
It’s normal for genitals to look different from person to person. There is a wide range of “normal.” For example, penises vary in color, length, girth, and shape – some point straight, others curve slightly, and sizes can differ widely. Labia are also unique for each person; they can be different colors or sizes, and the inner labia may be tucked inside or stick out. In puberty, one testicle often grows or hangs lower than the other, which is completely normal.
Common myths often cause confusion:
Myth: All boys with erections want sex.
-> Reality: Boys go through hormonal changes, so erections can happen even without sexual thoughts. Puberty may bring random erections and “wet dreams” (nighttime ejaculations) during sleep, which are normal. Having an erection doesn’t always mean a boy wants to have sex at that moment.
Myth: You can tell if someone is a virgin by their genitals (like an “intact hymen”).
-> Reality: The hymen is just a thin tissue around the vaginal opening that varies a lot. It can stretch or tear from many activities (sports, tampon use, even bending or biking). It often changes during growth. It is not a reliable sign of past sexual activity; only the person themselves knows their sexual history.
Myth: Genitals should look a certain way.
-> Reality: There is no one “correct” shape or size. A variety of sizes and shapes for penises or vulvas are normal. Health professionals say that differences in skin color, curves, or small skin folds are all normal.
If something is painful or very unusual (like a sudden bump or severe pain), talk to a doctor, but most variations are completely healthy.
Overall, knowing that bodies differ is key. Breasts, butts, genitals, and hair can look or grow differently for everyone. All these differences are normal and natural, and they don’t determine one’s value or ability to have healthy sex.
Why Knowing Your Body Matters for Safe Sex
Understanding your body helps you make smart choices about your health and safety. Practicing safe sex means using protection like condoms to reduce the risk of STIs (sexually transmitted infections) and unwanted pregnancy. The Cleveland Clinic advises young men to “practice safe sex” and use condoms for STI protection. Getting vaccinations (like the HPV vaccine) and regular check-ups are also recommended. Knowing how your genitals usually look, feel, and function helps you notice if something changes (like pain, lumps, or abnormal discharge) so you can seek medical advice early.
Sex education experts (like the WHO) emphasize that young people who are well-informed about their bodies and sexuality tend to make safer choices. Studies show they are more likely to delay sex until they feel ready and to use protection when they do have sex [1]. In short, learning about your anatomy gives you confidence. It helps you communicate with partners (for example, about what you feel comfortable with or what protection to use) and lets you take charge of your sexual health. Knowing your body is the first step toward being healthy and safe.
References
Cleveland Clinic. (2023). Vulva. Cleveland Clinic Health Library.
Cleveland Clinic. (2023). Penis. Cleveland Clinic Health Library.
Cleveland Clinic. (2023). Female Reproductive System. Cleveland Clinic Health Library.
Cleveland Clinic. (2023). Male Reproductive System. Cleveland Clinic Health Library.
Raising Children Network. (n.d.). Physical changes in puberty. raisingchildren.net.au.
World Health Organization. (2023). Comprehensive sexuality education. WHO.
[1] Comprehensive sexuality education
https://www.who.int/news-room/questions-and-answers/item/comprehensive-sexuality-education