Pre-birth

During embryogenesis, layers of cells known as germ cells are formed. Skin will eventually be formed by the cells in two of these layers; the ectoderm forming (amongst other structures) the epidermis and the mesoderm the dermis.

The baby is protected in utero by a thick layer of vernix caseosa, a very effective greasy substance which protects the infant’s skin from the watery environment of the amniotic fluid. The words vernix caseosa come from a Latin derivation, vernix, meaning ‘varnish’ and caseosa ‘cheesy’. The vernix is composed of sebum, which is secreted from the baby’s sebaceous glands from around 20 weeks, and skin cells as they desquamate. Further protection is provided by the fine, downy hair known as lanugo. This falls out soon after birth to be replaced with vellus and terminal hairs.