Know the Facts of Sexual Development

All of us go through a lot of changes during our teenage years. We change from girls and boys into women and men. Our bodies change. So do our feelings about ourselves, our families and our friends. Adjusting to these changes can be difficult. It's natural to feel confused and anxious when you're experiencing something for the first time.

The more you know the facts about the changes you're experiencing, the easier your life is going to be. Whether you're just beginning your teen years or about to finish them, it's important to understand how your body has changed in the past, is changing now and will change in the future. This leaflet presents information you need to know.

YOUR SEXUAL ANATOMY

Learning about sexual anatomy will help you understand sexual development. While most teens may think they already know the facts, many don't. Many don't even know the correct names for parts of their own bodies. Being ignorant about your body will probably contribute to your confusion, anxiety, fear and embarrassment about sexuality. Take the time to become sexually literate. Read this leaflet and don't be afraid to ask questions about things you don't understand.

A person's external genitals are located in the front of the body between the legs. The entire area of the external female genitals is called the vulva and is illustrated in Figure 1. You can see the clitoris and hood of the clitoris. The head of the clitoris can often only be seen when a fold of skin (hood) is gently pushed up. Not much of the clitoris is visible because it is covered by the labia and extends inside the body. Stimulation to this highly sensitive area can provide a lot of pleasure.

Just below the clitoris is the very small urinary opening known as the urethra and below that is the opening of the vagina. The anus, through which the bowels empty, is still lower. You'll also notice the labia majora and labia minora. The labia majora, often called the "outer lips," extends from above the clitoris down to below the vaginal opening. They include a fold of skin on each side which usually meet and cover the urinary and vaginal openings. The labia minora or inner lips are inside the outer lips and extend from just above the clitoris to below the vaginal opening. While they are called "inner lips," it is not unusual for them to protrude beyond the outer lips.

A female's vagina connects her external genitals to the internal reproductive system (see Figure 2). The cervix is at the top of the vagina and is the neck of the uterus. The uterus, or womb, is a cavity whose purpose is to hold a fetus until birth. Two fallopian tubes lead from the uterus and connect it to the ovaries which produce both eggs, or ova, and female hormones.

The male external genitals, which are easier to see than the vulva, are illustrated in Figure 3. The penis hangs away from the male's body. The glans is at the tip of the penis. Sometimes it is covered by the foreskin and sometimes it isn't. When it isn't, chances are it was removed soon after the baby was born in an operation called "circumcision." The scrotum is a sac which hangs beneath the penis and contains two testicles.

The testicles are part of the internal male reproductive system, which is shown in Figure 4. They produce male reproductive cells called sperm as well as male hormones. The vas deferens is a duct that carries sperm away from the testicles. Two glands, the seminal vesicles and the prostate, produce a milky fluid called semen which carries the sperm through the urethra and out the end of the penis. The urethra also is connected to the bladder and carries urine, though never at the same time as it carries semen and sperm.

PUBERTY

While you've probably heard people use the term "puberty," you may not know exactly what it means. Puberty refers to gaining the ability to reproduce and includes a variety of physical, psychological and social changes.

Our bodies produce chemicals called hormones which guide the physical changes we experience during puberty. Two hormones, estrogen in girls and testosterone in boys, direct the sexual development of young women and men.

It's important to realize that not everyone reaches puberty at the same time. Puberty can begin as early as age 8 or as late as age 15. Girls generally reach puberty earlier than boys. The age at which puberty begins is affected by the age your parents reached puberty, nutrition, percent body fat and a host of other factors.

Many teenagers worry that they are developing too slow or too fast. They become anxious and embarrassed about their bodies. What's important to realize is that it's normal for everyone to be different when it comes to growing up. Learning about the stages of sexual development can help you become more comfortable with the changes taking place in your body. Knowing what's happening to your body and what to expect can lessen your worries.

FEMALE SEXUAL DEVELOPMENT

The physical changes females experience during puberty can be outlined in four stages. These stages are best thought of as guidelines since all girls do not follow the same identical pattern or develop at the same rate.

• Sometime between ages 8 and 11. Hormones signal the ovaries and other internal reproductive organs to start growing. This increases the amount of estrogen produced.

• Sometime between ages 9 and 15. The darker area around the nipple known as the areola and then the breasts increase in size and develop a more rounded shape. While still sparse, pubic hair, which grows between the legs, becomes darker and coarser. Body fat continues to round body contours as growth in height continues. Normal vaginal discharge becomes noticeable. Acne may appear as sweat and oil glands become more active. The vagina becomes longer and the labia more pronounced as both internal and external reproductive organs and genitals grow.

• Sometime between ages 10 and 16. Both the areola and nipples grow. Pubic hair begins to take a triangular shape and underarm hair appears. The first menstrual flow or period occurs. As internal organs continue to develop, the ovaries may begin to produce mature eggs that are capable of being fertilized. Growth in height occurs more slowly.

• Sometime between ages 12 and 19. Breasts approach adult size and shape and pubic hair spreads to the top of the thighs. The voice may deepen slightly and menstrual cycles gradually become more regular.

• It's normal for females to experience increased sexual desires, dreams, fantasies and arousal during puberty. As a female becomes sexually excited, her vagina becomes wet. When she becomes very excited, she has an orgasm. Orgasm occurs when sexual tension reaches its peak and is suddenly discharged. This extremely pleasurable, involuntary response lasts a few seconds.

MENSTRUATION

Beginning menstruation is one of the most significant events of puberty for young women and usually begins between the ages of 10 and 16. It's important to understand why and how it occurs.

The ovaries usually produce one egg each month. After the egg is released, known as "ovulation," it travels down one fallopian tube towards the uterus which has been preparing for pregnancy by becoming full of extra blood and other tissue to support a developing, fertilized egg. If the egg and sperm join together in the fallopian tube, fertilization occurs. Pregnancy then begins if the fertilized egg attaches itself to the lining of the uterus.

Most of the time this doesn't happen, however. The egg does not meet a sperm and it begins to break apart before it gets to the uterus. In this case, the tissue and blood which line the uterus aren't needed and they flow out the uterus, through the cervix and vagina and out of the body. This is what is known as menstrual flow or "having a period."

One of the most important things for girls to understand is that menstruation is normal and healthy. While blood is a sign of injury or disease in other circumstances, in this case, it's a sign they are growing up. It's also important for girls to realize that they can manage their menstrual flow without disrupting other aspects of their lives such as school athletics and social events.

Sanitary pads or tampons are used to absorb the menstrual flow. Pads stay in place by an adhesive strip that sticks inside the underwear. A tampon, on the other hand, fits inside the vagina and is held in place by the vaginal walls. The tampon has a string that hangs out of the vagina and it is easily removed by pulling the string. Pads and tampons are available in drugstores and supermarkets and come with instructions on how to use them.

Teenagers should not be surprised if their periods vary in how long they last or how far apart they occur. It's normal for young women to have an irregular pattern of menstrual cycles when they first begin menstruation. In fact, it's not unusual for three to six months to go by between periods. It can take up to seven years for young women to establish their regular, more predictable cycles when they probably will have a menstrual flow every four or five weeks.

While most women and girls do not have severe problems with menstruation, some do have cramps the first day or two of their periods. A girl who has bad cramps or a menstrual flow that seems unusually heavy should talk to her parents, a school nurse, doctor or teacher. Medicine can be taken to reduce the pain of menstrual cramps.

In addition, some females may experience physical or emotional discomfort before their periods begin. This is known as "premenstrual syndrome" (PMS) and is due to hormonal changes that occur the week or so before their periods begin. Eating a healthy diet and engaging in moderate exercise reportedly reduce the symptoms of PMS for some. Since PMS is a treatable physical problem, it's a good idea to talk to a doctor if symptoms continue.

MALE SEXUAL DEVELOPMENT

The physical changes that males experience during puberty can be outlined in four stages. Think of the stages as guidelines. Not all boys follow the same identical pattern or develop at the same rate.

• Sometime between ages 9 and 15. The first noticeable change occurs when the testicles begin to grow, the scrotum becomes redder and coarser, and a few pubic hairs appear at the base of the penis. Body shape changes as the hormone testosterone causes muscle mass to develop and height increases. The circle of darker skin around the nipple (areola) grows larger and darker.

• Sometime between ages 11 and 16. The testicles and scrotum continue to grow and the penis becomes longer. Pubic hair becomes both coarser and more curled and spreads to cover the area between the legs. The body increases in height, the shoulders broaden and the hips narrow. The voice begins to deepen as the voice box or larynx becomes larger. Sparse facial and underarm hair appear.

• Sometime between ages 11 and 17. The testicles continue to increase in size and the penis begins to increase in circumference as well as in length. Growth of underarm and facial hair increases and shaving may begin. The internal reproductive organs mature enough to produce the first ejaculation of semen and sperm.

• Sometime between ages 14 and 18. The body nears its final adult height and the genitals achieve their adult size and shape. Pubic hair spreads to the thighs and upward towards the stomach. Chest hair appears. Shaving becomes more frequent as facial hair reaches its full growth. Height, body hair, muscle growth and strength continue to increase into the twenties for some young men.

Males, like females, experience increased sexual desires, dreams, fantasies and arousal during puberty. As a male becomes sexually excited, his penis fills with blood and gets hard and erect. When he becomes very excited, he too has an orgasm and a sticky liquid spurts out the end of his erect penis. This pleasurable experience is also called ejaculation or "coming." The sticky liquid is semen or "cum" and contains sperm which were made in the testicles. Usually, about a teaspoon of semen is released at a time. Every drop of healthy semen contains millions of invisible sperm. Even the semen that oozes out of the penis before ejaculation contains sperm and can cause pregnancy.

Most boys and men have erections and ejaculate in their sleep. This often occurs when they have sexual dreams and is called a "wet dream." While they may come as a surprise to a male who is not prepared for them, wet dreams are healthy, cannot be controlled and should not be a cause for concern.

Young men also often have erections in nonsexual situations or for no reason at all. While they can be embarrassing, it's important to realize that they are normal and a sign of good health. They usually go away in a few minutes if you stop worrying about them. A hard penis will become soft again even without an orgasm or ejaculation.

ACCEPT YOUR BODY

Some teenagers react to all the changes going on in their bodies by becoming very anxious and self-conscious. They don't like the way they look or worry that the changes they are experiencing are not "normal."

Young women are particularly likely to worry about their breasts. They worry about breasts that are too big, too small or don't match. These women should try to accept their breasts as they are. They shouldn't judge themselves against the bodies they see in magazines or on television. Breasts, like all body parts, naturally come in a wide variety of shapes and sizes. In fact, more than half of all women have visible size differences between their own two breasts. Regardless of shape or size, a woman's breasts can give her sexual pleasure when they are touched. Because they are mammary glands, they produce milk after the birth of a baby. The size of a woman's breasts does not affect the amount of milk she produces.

Similarly, young men are likely to be worried about the size of their penises and testicles. They often worry that they are too small. These males need to simply accept themselves as they are. There is no magical "normal" size. There simply is a variety of sizes and shapes. Although it can be shorter or longer, the erect penis usually varies from four to eight inches long. About six inches is average, regardless of size when not erect. Penis size does not determine the sexual enjoyment of either a male or his sexual partner.

If you're concerned, anxious or worried about the way your body looks, try to understand that being masculine, feminine, cute, attractive or sexy depends far more on personality than the size and shape of any part of your body. How you think about yourself, take care of yourself and treat other people are far more important than any physical characteristic.

SEXUAL DEVELOPMENT AND INTEGRITY

We hope this fact sheet has helped you understand and feel good about the physical changes you will be or have been experiencing during your teenage years. As we've already mentioned, it's common to experience increased sexual desires, dreams, fantasies and arousal. You cannot control these feelings. They're healthy and a sign you're growing up. What you need to do now is learn how to manage those feelings. You need to make responsible sexual decisions about your sexual behavior. That's what the "Sexual Integrity for Teens" fact sheets are designed to help you do. If you haven't already done so, read the rest of this series.

AUTHOR: Gary L. Hansen, Ph.D., Extension Specialist in Sociology, Cooperative Extension Service, University of Kentucky; and William W. Mallory, Fayette County Extension Agent for 4-H/Youth Development, Cooperative Extension Service, University of Kentucky.