I will praise thee; for I am fearfully and wonderfully made.
Psalm 139:14
"Skin is constantly shedding cells, yet does not leak fluids.
Why is that?
---Leakage would be lethal.
---This mystery has baffled researchers for
decades.
The three main skin layers of humans are the outer layer, the avascularized epidermis, the middle layer, containing the stratum granulosum, and the bottom layer, the subcutaneous fat, or hypodermis.
The epidermis is made of a thick outer barrier of
dead epidermal cells, which are constantly shed. This outer layer is the
main skin 
barrier which gives skin its color. It contains specially
designed immune cells. In the dermis below the epidermis, the stratum granulosum is constructed out of a single layer of cells. Although much thinner than the other two layers, it serves as the fluid barrier.
Cells called keratinocytes divide at the lowest epidermis level.
These new cells gradually push to the top layer where they are sloughed
off by normal living activities. When the top dead layer, the stratum corneum, breaks away from the epidermis and falls off, it makes room for the newer cells growing below.
During a 24-hour period, a person loses almost five billion skin cells,
which becomes the main composition of common house dust. It “has been a
challenge for scientists to explain how this colossal shedding process
can occur without there being a break in the skin barrier.”
The shape of cells in the stratum granulosum combined with their ability
to temporarily ‘glue’ themselves together helps explain how they form
this strong barrier.
The shape of these cells is a flattened version of a
tetrakaidecahedron, a 14-sided 3-D solid made out of six rectangular
and eight hexagonal sides. The Yokouchi study determined
the shape by studying skin cells with both confocal and two-photon
excitation microscopy (TPEF or 2PEF).
Historically, the great Scottish
physicist William Thomson, better known as Lord Kelvin
concluded in 1887 that the flattened tetrakaidecahedron (f-TKD) was the
best design for packing equal-sized objects together to fill a space
with minimal surface area." CEH