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Integumentary Development of the Fetus

Consisting of the skin and all its dermal layers, sebaceous and sudoriferous glands, hair, nails, and nerve receptors, the integumentary system is our body's largest organ system. The development of the integumentary system begins when a baby is still considered an embryo. During the second trimester, when the baby is referred to as a fetus, the development of the integumentary system is well underway and continues until birth.

  1. Functions of the Integumentary System

    • The most important functions of the integumentary system are protecting internal structures and organs and preventing the entry of bacteria and organisms that cause illness or disease. Imagine how vulnerable our bodies would be without skin. The integumentary system also produces vitamin D, helps to control our body temperature and protects us from the suns powerful UV rays.

    Skin and Glands

    • A fetus begins to develop sweat glands on his hands and feet around the end of the fourth month. The skin however, goes through a few phases. During the fourth month, the fetus's skin is transparent, bright pink, and covered with soft hair. Around the end of the fifth month, the skin will be covered with languo--a white, thin hair that often remains until a few days after birth. By the end of the sixth month, the fetal skin develops vernix. Vernix is a waxy coating that protects the skin while it is in the womb. Early in the third trimester, the skin is red and wrinkled and a layer of fat is developing underneath. Throughout the third trimester, the skin becomes smooth and pink.

    Hair and Nails

    • Nails begin growing in a fetus by the end of the twelfth week. Before the ninth month arrives, the nails will be grown past the tips of their fingers. Coarse hair starts to grow on the fetus during the fifth month (languo appears earlier). This is when hair will be present on the head and includes the eyelashes and eyebrows.

    Nerve Receptors

    • The nerve receptors develop throughout pregnancy and should all be fully functioning at birth. These nerve receptors allow the baby to "feel" different sensations. This includes the ability to sense different temperatures, experience pain, or feel his mother's tender touch.

    Skin Color

    • The integumentary system is also responsible for developing the chemicals that create the pigmentation of the skin, or skin color. While the fetus is developing these chemicals during the earlier weeks, the fetus does not gain his true skin color until around the thirty-seventh week.

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