CyberSurgeons Live Mission

The Reproductive System

Student Pages

The human reproductive system allows for the production of offspring and the continuation of the species.  Males and females have distinct reproductive organs and glands which form gametes (sperm in males, eggs, or ova, in females) which unite to form the embryo.  The embryo develops in the female’s uterus during the gestational period.

The reproductive system is controlled by chemicals called hormones.  Hormones, released by endocrine glands, work by the negative feedback mechanism.  The level of hormones in the blood must reach a certain threshold amount for the response to occur.  Once the level of hormone in the blood has been achieved, the response occurs and is long-lasting.  The response will continue until the level of the chemical decreases enough to stop the response. This mechanism is called the negative feedback mechanism because when the level decreases, the feedback stops the effects.

Remember, some glands are exocrine glands because they secrete chemicals through ducts. Endocrine glands are ductless glands; they secrete chemicals directly into the blood. Blood then transports the hormones to all parts of the body, but the hormone only has an effect on target cells.  Target cells are specific to the hormone; a hormone specific to a target cell can only affect that target tissue because of the presence of receptors for the hormone on the target cells.

In the reproductive system for example, the pituitary gland (endocrine) releases FSH (follicle stimulating hormone) directly into the blood. The hormone then produces a response in its target tissue (the ovaries in females) by controlling development of the follicles containing immature eggs; in males, the target tissue is the testes and FSH controls the development of sperm. 

As another example, consider the pituitary gland’s release of LH (luteinizing hormone) which stimulates the ovaries (the target tissue) to release an egg. 

The following table summarizes the secreting glands, hormones, and functions of the reproductive system.




Adrenal Gland


►stimulates the early development of reproductive organs

►supplements primary sex hormones from the gonads (sex organs)

Pituitary Gland

Prolactin  (PRL)

►sustains milk production after birth


Follicle-stimulating hormone


►in females, controls development of eggs in ovaries

►in males, controls development of sperm cells

Luteinizing hormone


►controls hormones that promote the release of an egg cell in females

Oxytocin (OT)

►contracts smooth muscles in the uterine wall






►develops and maintains female secondary sex characteristics




►promotes changes in uterus during the reproductive cycle





►controls development of male secondary sex characteristics


The Male Reproductive System

The primary male reproductive organ is the testes which form male gametes (sperm).  The testes are located in the scrotum, a sac located outside the body cavity.  Being located outside the body cavity allows for the optimal temperature for sperm production—about 3 0 lower than normal body temperature.

Sperm develop in tightly coiled tubules in the testes through the process of meiosis (gamete production that halves the number of chromosomes found in somatic cells).  A sexually mature male can produce approximately 300 million sperm per day.

Sperm move out of the testes through a tube in the scrotum called the epididymis where they finish the maturation process.

Fluid released from seminal vesicles (located at the base of the urinary bladder) mixes with the sperm as they are released from the epididymis.  The fluid is high in fructose, a sugar that provides energy for the sperm.

The prostate gland (located near the top of the urethra) releases a fluid that is much more alkaline. This alkaline fluid helps the sperm move.

Bulbourethral glands (located beneath the prostate gland) secrete an alkaline fluid which also helps the sperm survive not only the acidic environment of the urethra, but also the acidic environment of the female vagina.

(The fluid from each of these glands along with the sperm is called semen).

When they are to be released from the body, they travel through the vas deferens to the urethra. The urethra is a tube in the penis through which the sperm are transported out of the body.  (The urethra also releases urine from the body, but a muscle at the base of the urinary bladder closes off and does not allow urine and sperm to mix.

The Female Reproductive System

The primary female reproductive organ is the ovary.  Females have 2 ovaries, each about the size of a walnut, located on either side of the lower abdominal cavity.  The ovaries produce an ovum, or egg usually with the onset of puberty.

Usually, one egg is produced from one of the ovaries during every other menstrual cycle (approximately one/month). The immature egg develops in the ovary and is released into the fallopian tube, or oviduct. 

The egg travels through the oviduct by peristalsis and moving cilia lining the tube toward the uterus

If fertilization by a sperm occurs, it occurs here in the oviduct and the fertilized egg continues to move to the uterus. At this time of the cycle, the uterus has a thick lining of blood-filled capillaries which could support a fertilized egg. 

If fertilization does not occur, the egg does not implant in the uterus and the hormonal changes signal the sloughing off the uterine lining (the menstrual cycle).

The uterus narrows at the distal end to the cervix, the opening from the uterus to the vagina.  The vagina is the passageway between the uterus and the outside of the female body.


Primary sex characteristics are the reproductive organs, such as the testes in males, and the ovaries in females.  Secondary sex characteristics are those characteristics that are associated with being distinctly male or distinctly female.  In the male, hair begins to grow on the face and chest, the voice deepens due to a thickening of the vocal folds, the skin thickens, muscular growth increases, the shoulders broaden, the waist narrows, the bones thicken and strengthen, and sperm production begins.  In the female, breasts develop along with the ducts of the mammary glands, the waist narrows, the hips broaden, and fat tissue is deposited under the skin to help make estrogen from adrenal gland secretions, and the menstrual cycle begins.

The time when the secondary sex characteristics begin to develop is called puberty. Changes associated with puberty are controlled by hormones from the endocrine system.

Check for Understanding

  1. What is the function of the reproductive system?




  3.  What is the function of the following parts/organs of the reproductive system?

    a. ovaries—

    b. oviducts—

    c. uterus—

    d. testes—

    e. epididymus—

    f. prostate gland—

    g. cervix—

    h. vas deferens—

    i. scrotum—





  5.  What is the difference between primary sex characteristics and secondary sex characteristics?   




  7. Complete the following table to list examples of male and female secondary sex characteristics.

Female Secondary Sex Characteristics

Male Secondary Sex Characteristics













Overview| Pre-Mission Lesson Plans| Support Curriculum| Mission Materials| Resource Center

WJU| CET| CLC| NIH| SEPA| Credits| Schedule a Mission