The human amnion was examined by means of light microscopy and scanning and transmission electron microscopy. The surface shows apart from microvilli a particular structure, called "blebs"; the intercellular junction is formed by desmosomes and a labyrinthine channel system, and at the base pedicels extend into the basement membrane. Cell shedding uncovers the basement membrane which seems to play a primordial role in preserving the intact amniotic cavity. These data underline the complex structure and the multiple role the amnion performs during gestation.