By use of cryofracture and scanning electron microscopy of human amnio
chorion we have captured images of all the major layers of the tissue.
Correlation of confocal and electron-microscope data has allowed grea
ter understanding of how these cellular and acellular layers interconn
ect in order to maintain their integrity as a multilaminar tissue. Thi
s is not straightforward as mutual sliding or area change is required
of concentric curved surfaces which expand and contract as does the am
nion. In this paper we suggest a mechanism by which the amnion is able
to slide with respect to the chorion and still maintain continuity as
a structural unit. It is based on the observation of complementary gy
ri and sulci on surfaces facing the spongy layer which is a shear plan
e. Cellular detail at higher resolution of the amniotic epithelium and
acellular layers provides a more complete description of structural c
omposition than was previously available.