Endothelial cell crystalloids in newborn human foreskin

This study describes the presence of crystalline inclusions in the endothelial cells of foreskins. They were found in 9 normal full-term newborn infants, without maternal medication or complication during pregnancy and delivery. These cytoplasmic crystalloids occurred in 10% of endothelial cells of small blood vessels. The diameter of the inclusions ranged from 0.3 to 1.5 micron and they appeared as round, oval, hexagonal or irregular polygonal in shape. These inclusions were surrounded by a triple membrane and their contents demonstrated granular, homogeneous and crystalloid-like material with a regular periodicity of dense and less dense layers measuring about 20-25 nm. Similar crystalloids in the endothelial cells were observed in the normal upper lip skin of a 6-week-old girl, although they were present in much smaller numbers than in foreskin. No endothelial inclusions were found in normal skin taken from 11 body areas in 29 patients aged 2.5 to 56 years. The nature and function of these cytoplasmic crystalloids are unknown.